Enhanced sounding for secure mode wireless communications

ABSTRACT

This disclosure describes systems, methods, and devices related to enhanced sounding for secure mode wireless communications. A device may generate a channel sounding symbol comprising a first subcarrier and a second subcarrier, wherein a first amplitude of the first subcarrier is different than a second amplitude of the second subcarrier. The device may generate a channel sounding signal comprising the channel sounding symbol. The device may send the channel sounding signal to a second device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to and claims priority to U.S. ProvisionalPatent Application No. 63/001,237, filed Mar. 27, 2020, to U.S.Provisional Patent Application No. 63/006,216, filed Apr. 7, 2020, toU.S. Provisional Patent Application No. 63/012,534, filed Apr. 20, 2020,to U.S. Provisional Patent Application No. 63/021,836, filed May 8,2020, and to U.S. Provisional Patent Application No. 63/023,558, filedMay 12, 2020, all disclosures which are hereby incorporated herein byreference in their entirety.

TECHNICAL FIELD

This disclosure generally relates to systems and methods for wirelesscommunications and, more particularly, to enhanced sounding for securemode wireless communications.

BACKGROUND

Wireless devices are becoming widely prevalent and are increasinglyrequesting access to wireless channels. The Institute of Electrical andElectronics Engineers (IEEE) is developing one or more standards thatutilize Orthogonal Frequency-Division Multiple Access (OFDMA) in channelallocation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a network diagram illustrating an example network environment,in accordance with one or more example embodiments of the presentdisclosure.

FIG. 2A depicts a schematic diagram for a trigger-based channel soundingprocess, in accordance with one or more example embodiments of thepresent disclosure.

FIG. 2B depicts a schematic diagram for a non-trigger-based channelsounding process, in accordance with one or more example embodiments ofthe present disclosure.

FIG. 3A depicts an illustrative system for a channel sounding process,in accordance with one or more example embodiments of the presentdisclosure.

FIG. 3B depicts an illustrative system for a channel sounding processwhen an attacker exists, in accordance with one or more exampleembodiments of the present disclosure.

FIG. 4A depicts a signal constellation using phase shift keying, inaccordance with one or more example embodiments of the presentdisclosure.

FIG. 4B depicts a signal constellation using quadrature amplitudemodulation, in accordance with one or more example embodiments of thepresent disclosure.

FIG. 5A depicts an example technique for enhanced channel sounding, inaccordance with one or more example embodiments of the presentdisclosure.

FIG. 5B depicts an example technique for enhanced channel sounding, inaccordance with one or more example embodiments of the presentdisclosure.

FIG. 5C depicts an example technique for enhanced channel sounding, inaccordance with one or more example embodiments of the presentdisclosure.

FIG. 5D depicts an example technique for enhanced channel sounding, inaccordance with one or more example embodiments of the presentdisclosure.

FIG. 5E depicts an example technique for enhanced channel sounding, inaccordance with one or more example embodiments of the presentdisclosure.

FIG. 5F depicts an example technique for enhanced channel sounding, inaccordance with one or more example embodiments of the presentdisclosure.

FIG. 5G depicts an example technique for enhanced channel sounding, inaccordance with one or more example embodiments of the presentdisclosure.

FIG. 6A depicts an example technique for enhanced channel sounding, inaccordance with one or more example embodiments of the presentdisclosure.

FIG. 6B depicts an example technique for enhanced channel sounding, inaccordance with one or more example embodiments of the presentdisclosure.

FIG. 6C depicts an example technique for enhanced channel sounding, inaccordance with one or more example embodiments of the presentdisclosure.

FIG. 6D depicts an example transformation matrix for enhanced channelsounding, in accordance with one or more example embodiments of thepresent disclosure.

FIG. 6E depicts an example technique for enhanced channel sounding, inaccordance with one or more example embodiments of the presentdisclosure.

FIG. 6F depicts an example technique for enhanced channel sounding, inaccordance with one or more example embodiments of the presentdisclosure.

FIG. 6G depicts an example technique for enhanced channel sounding, inaccordance with one or more example embodiments of the presentdisclosure.

FIG. 6H depicts an example technique for enhanced channel sounding, inaccordance with one or more example embodiments of the presentdisclosure.

FIG. 6I depicts an example technique for enhanced channel sounding, inaccordance with one or more example embodiments of the presentdisclosure.

FIG. 6J depicts an example technique for enhanced channel sounding, inaccordance with one or more example embodiments of the presentdisclosure.

FIG. 7 illustrates a flow diagram of illustrative process for enhancedchannel sounding, in accordance with one or more example embodiments ofthe present disclosure.

FIG. 8 illustrates a functional diagram of an exemplary communicationstation that may be suitable for use as a user device, in accordancewith one or more example embodiments of the present disclosure.

FIG. 9 illustrates a block diagram of an example machine upon which anyof one or more techniques (e.g., methods) may be performed, inaccordance with one or more example embodiments of the presentdisclosure.

FIG. 10 is a block diagram of a radio architecture in accordance withsome examples.

FIG. 11 illustrates an example front-end module circuitry for use in theradio architecture of FIG. 10, in accordance with one or more exampleembodiments of the present disclosure.

FIG. 12 illustrates an example radio IC circuitry for use in the radioarchitecture of FIG. 10, in accordance with one or more exampleembodiments of the present disclosure.

FIG. 13 illustrates an example baseband processing circuitry for use inthe radio architecture of FIG. 10, in accordance with one or moreexample embodiments of the present disclosure.

DETAILED DESCRIPTION

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, algorithm, and other changes. Portions and features of someembodiments may be included in, or substituted for, those of otherembodiments. Embodiments set forth in the claims encompass all availableequivalents of those claims.

In wireless communications defined by the IEEE 802.11 technicalstandards, the very high throughput (VHT) null data packet (NDP)Sounding-based 802.11az protocol is referred to as VHTz, and the highefficiency (HE) null data packet (NDP) Sounding-based 802.11az protocolis referred to as HEz. In wireless communications defined by the IEEE802.11 technical standards, the very high throughput (VHT) null datapacket (NDP) Sounding-based 802.11az protocol is referred to as VHTz,the and high efficiency (HE) null data packet (NDP) Sounding-based802.11az protocol is referred to as HEz. VHTz is based on the 802.11acNDP and is a single user sequence, whereas HEz is based on 802.11ax NDPand 802.11az NDP and it supports multiuser operations.

In IEEE 802.11 communications, channel sounding refers to a process thatallows devices to evaluate radiofrequency (RF) channels used forwireless communications. The IEEE 802.11 technical standards defineprocesses for devices to exchange packets, such as NDPs, and use theNDPs to determine channel characteristics, determine relative devicepositions, and identify attempted attacks.

The 802.11az secure mode considers secure communications to address newattack models. For example, an attacker listens to the beginning portionof the sounding symbol used in channel sounding and detects whichsounding signal is being sent. The attacker then sends the remainder ofthe sounding signal with a time shift such that the attacker's “fake”sounding signal arrives at an intended receiver with a fake channelarrival that is detected at the intended receiver. In this manner, anattacker may mimic a transmission from a non-attacker (e.g., “real”device) by sending a similar transmission to a receiving device, andtiming the reception of the fake transmission to arrive just before thereal transmission is to occur. The fake transmission from the attackermay result in the receiving device determining that the sender of the“real” transmission (the non-attacker) is closer to the receiving devicethan it actually is, thereby subjecting the receiving device to securityvulnerabilities (e.g., unlocking for the attacker, etc.). To countersuch attack attempts, enhanced feedback information may be provided froma sounding receiver to a sounding transmitter to allow for devices todetect attempted attacks.

One known solution to detect attacks is for a device to perform aconsistency check on the channels estimated based on multiple channelsoundings within the channel coherence time. A receiver device can checkthe power fluctuation in the residual interference and noise aftercancelling out superimposed sounding signals from a received signal. Ifthere is a significant power fluctuation, an alert may be triggered sothat the ranging security gets protected.

Because the attacker may detect which sounding signal is sent with asmall fraction of the sounding signal, some existing solutions may notdetect the attack accurately. Some channel bandwidth may be wasted dueto high false alarm rates (e.g., false positive attack detections).

Example embodiments of the present disclosure relate to systems,methods, and devices for Enhanced Sounding for 802.11az Secure Mode.

In one embodiment, an enhanced sounding for secure mode system mayfacilitate multiple attack mitigation enhancements. The firstenhancement extends the current constant modulus constellation (i.e.,8PSK or QPSK) to higher order quadrature amplitude modulations (QAMs).One solution is to add a magnitude variation to a sounding signal sothat the attacker cannot easily detect the sounding signal. The secondsolution extends the time-domain pulses to time-varying waveforms sothat the information bits of the sounding signal are mixed together inboth the frequency and the time domain. As a result, the attacker cannotbreak the search space in either the time or the frequency domain, andthe attacker has to do a joint search in a space prohibitively large.The present disclosure provides multiple options to make the soundingsignal carry more and more information so that the attacker cannotdetect the sounding signal with a high success rate. The options mayincrease the signal mixing or entropy in both the frequency and timedomains so that the attacker cannot use a frequency-time transformationto reduce the search space.

In one embodiment, an attack mitigation solution represents an extensionof the 802.11az channel sounding signal. In 802.11az, each subcarrier ofan NDP sounding symbol may have the same magnitude (e.g., amplitude).The solution to mitigate attempted attacks may allow magnitude changesacross the subcarriers of an NDP sounding symbol. For example, 16-, 64-,256-, 1024-, or higher order QAMs may be used. As a result, not only thenumber of phases increases from the 8PSK or QPSK, but also the magnitudecarries additional bits (e.g., 8PSK carries three bits per symbol while16PSK carries four bits per symbol). Therefore, the entropy of asounding signal (e.g., an NDP with one or more sounding symbols)increases. The selection of the constellation point on each activesubcarrier of an NDP sounding symbol may be determined by the outputbits of a cypher as defined in 802.11az. Even though the attacker onlyobserves the beginning part of the sounding signal, the attacker maystill perform frequency-domain detection by converting the time-domainsignal to the frequency domain (e.g., by a windowed Fast FourierTransform). Because the windowed Fast Fourier Transform (FFT) introducesinter-subcarrier interference, the attacker needs some computation powerto detect the QAM symbols on the subcarriers. Other attack mitigationsolutions are described herein.

In 802.11az, channel sounding may send NDPs having one or more symbols(e.g., the number of symbols based on the number of spatial streams usedin transmission or based on the number of long trainingfields—LTFs—used). The NDP symbols may be preceded in the NDP by otherfields of the NDP, such as an HE-SIG-A field and an HE-STF field. Themagnitude of an NDP symbol included in the NDP, as currently defined by802.11az, may not vary from one subcarrier to another subcarrier.However, to make it more difficult to execute an attack using soundingsignals, the magnitude may be allowed to vary across the differentsubcarriers of an NDP symbol.

The current HE-LTF defined by the 802.11 standards consists of a fixedor predefined sequence of BPSK symbols across the active subcarriers,which are not random. The secure mode of 802.11az replaces the fixedBPSK symbol sequence with a random 64QAM symbol sequence. The 802.11azlong training field is referred to as HEz-LTF to be different from theconventional HE-LTF used in non-secure mode.

The proposed sounding signals enhance the security of 802.11az. The highcomplexity of detecting the sounding signal may deter attacks andprotect device and transmission security.

The above descriptions are for purposes of illustration and are notmeant to be limiting. Numerous other examples, configurations,processes, algorithms, etc., may exist, some of which are described ingreater detail below. Example embodiments will now be described withreference to the accompanying figures.

FIG. 1 is a network diagram illustrating an example network environment100, according to some example embodiments of the present disclosure.Wireless network 100 may include one or more user devices 120 and one ormore access points(s) (AP) 102, which may communicate in accordance withIEEE 802.11 communication standards. The user device(s) 120 may bemobile devices that are non-stationary (e.g., not having fixedlocations) or may be stationary devices.

In some embodiments, the user devices 120 and the AP 102 may include oneor more computer systems similar to that of the functional diagram ofFIG. 8 and/or the example machine/system of FIG. 9.

One or more illustrative user device(s) 120 and/or AP(s) 102 may beoperable by one or more user(s) 110. It should be noted that anyaddressable unit may be a station (STA). An STA may take on multipledistinct characteristics, each of which shape its function. For example,a single addressable unit might simultaneously be a portable STA, aquality-of-service (QoS) STA, a dependent STA, and a hidden STA. The oneor more illustrative user device(s) 120 and the AP(s) 102 may be STAs.The one or more illustrative user device(s) 120 and/or AP(s) 102 mayoperate as a personal basic service set (PBSS) control point/accesspoint (PCP/AP). The user device(s) 120 (e.g., 124, 126, or 128) and/orAP(s) 102 may include any suitable processor-driven device including,but not limited to, a mobile device or a non-mobile, e.g., a staticdevice. For example, user device(s) 120 and/or AP(s) 102 may include, auser equipment (UE), a station (STA), an access point (AP), a softwareenabled AP (SoftAP), a personal computer (PC), a wearable wirelessdevice (e.g., bracelet, watch, glasses, ring, etc.), a desktop computer,a mobile computer, a laptop computer, an ultrabook™ computer, a notebookcomputer, a tablet computer, a server computer, a handheld computer, ahandheld device, an internet of things (IoT) device, a sensor device, aPDA device, a handheld PDA device, an on-board device, an off-boarddevice, a hybrid device (e.g., combining cellular phone functionalitieswith PDA device functionalities), a consumer device, a vehicular device,a non-vehicular device, a mobile or portable device, a non-mobile ornon-portable device, a mobile phone, a cellular telephone, a PCS device,a PDA device which incorporates a wireless communication device, amobile or portable GPS device, a DVB device, a relatively smallcomputing device, a non-desktop computer, a “carry small live large”(CSLL) device, an ultra mobile device (UMD), an ultra mobile PC (UMPC),a mobile internet device (MID), an “origami” device or computing device,a device that supports dynamically composable computing (DCC), acontext-aware device, a video device, an audio device, an A/V device, aset-top-box (STB), a blu-ray disc (BD) player, a BD recorder, a digitalvideo disc (DVD) player, a high definition (HD) DVD player, a DVDrecorder, a HD DVD recorder, a personal video recorder (PVR), abroadcast HD receiver, a video source, an audio source, a video sink, anaudio sink, a stereo tuner, a broadcast radio receiver, a flat paneldisplay, a personal media player (PMP), a digital video camera (DVC), adigital audio player, a speaker, an audio receiver, an audio amplifier,a gaming device, a data source, a data sink, a digital still camera(DSC), a media player, a smartphone, a television, a music player, orthe like. Other devices, including smart devices such as lamps, climatecontrol, car components, household components, appliances, etc. may alsobe included in this list.

As used herein, the term “Internet of Things (IoT) device” is used torefer to any object (e.g., an appliance, a sensor, etc.) that has anaddressable interface (e.g., an Internet protocol (IP) address, aBluetooth identifier (ID), a near-field communication (NFC) ID, etc.)and can transmit information to one or more other devices over a wiredor wireless connection. An IoT device may have a passive communicationinterface, such as a quick response (QR) code, a radio-frequencyidentification (RFID) tag, an NFC tag, or the like, or an activecommunication interface, such as a modem, a transceiver, atransmitter-receiver, or the like. An IoT device can have a particularset of attributes (e.g., a device state or status, such as whether theIoT device is on or off, open or closed, idle or active, available fortask execution or busy, and so on, a cooling or heating function, anenvironmental monitoring or recording function, a light-emittingfunction, a sound-emitting function, etc.) that can be embedded inand/or controlled/monitored by a central processing unit (CPU),microprocessor, ASIC, or the like, and configured for connection to anIoT network such as a local ad-hoc network or the Internet. For example,IoT devices may include, but are not limited to, refrigerators,toasters, ovens, microwaves, freezers, dishwashers, dishes, hand tools,clothes washers, clothes dryers, furnaces, air conditioners,thermostats, televisions, light fixtures, vacuum cleaners, sprinklers,electricity meters, gas meters, etc., so long as the devices areequipped with an addressable communications interface for communicatingwith the IoT network. IoT devices may also include cell phones, desktopcomputers, laptop computers, tablet computers, personal digitalassistants (PDAs), etc. Accordingly, the IoT network may be comprised ofa combination of “legacy” Internet-accessible devices (e.g., laptop ordesktop computers, cell phones, etc.) in addition to devices that do nottypically have Internet-connectivity (e.g., dishwashers, etc.).

The user device(s) 120 and/or AP(s) 102 may also include mesh stationsin, for example, a mesh network, in accordance with one or more IEEE802.11 standards and/or 3GPP standards.

Any of the user device(s) 120 (e.g., user devices 124, 126, 128), andAP(s) 102 may be configured to communicate with each other via one ormore communications networks 130 and/or 135 wirelessly or wired. Theuser device(s) 120 may also communicate peer-to-peer or directly witheach other with or without the AP(s) 102. Any of the communicationsnetworks 130 and/or 135 may include, but not limited to, any one of acombination of different types of suitable communications networks suchas, for example, broadcasting networks, cable networks, public networks(e.g., the Internet), private networks, wireless networks, cellularnetworks, or any other suitable private and/or public networks. Further,any of the communications networks 130 and/or 135 may have any suitablecommunication range associated therewith and may include, for example,global networks (e.g., the Internet), metropolitan area networks (MANs),wide area networks (WANs), local area networks (LANs), or personal areanetworks (PANs). In addition, any of the communications networks 130and/or 135 may include any type of medium over which network traffic maybe carried including, but not limited to, coaxial cable, twisted-pairwire, optical fiber, a hybrid fiber coaxial (HFC) medium, microwaveterrestrial transceivers, radio frequency communication mediums, whitespace communication mediums, ultra-high frequency communication mediums,satellite communication mediums, or any combination thereof.

Any of the user device(s) 120 (e.g., user devices 124, 126, 128) andAP(s) 102 may include one or more communications antennas. The one ormore communications antennas may be any suitable type of antennascorresponding to the communications protocols used by the user device(s)120 (e.g., user devices 124, 126 and 128), and AP(s) 102. Somenon-limiting examples of suitable communications antennas include Wi-Fiantennas, Institute of Electrical and Electronics Engineers (IEEE)802.11 family of standards compatible antennas, directional antennas,non-directional antennas, dipole antennas, folded dipole antennas, patchantennas, multiple-input multiple-output (MIMO) antennas,omnidirectional antennas, quasi-omnidirectional antennas, or the like.The one or more communications antennas may be communicatively coupledto a radio component to transmit and/or receive signals, such ascommunications signals to and/or from the user devices 120 and/or AP(s)102.

Any of the user device(s) 120 (e.g., user devices 124, 126, 128), andAP(s) 102 may be configured to perform directional transmission and/ordirectional reception in conjunction with wirelessly communicating in awireless network. Any of the user device(s) 120 (e.g., user devices 124,126, 128), and AP(s) 102 may be configured to perform such directionaltransmission and/or reception using a set of multiple antenna arrays(e.g., DMG antenna arrays or the like). Each of the multiple antennaarrays may be used for transmission and/or reception in a particularrespective direction or range of directions. Any of the user device(s)120 (e.g., user devices 124, 126, 128), and AP(s) 102 may be configuredto perform any given directional transmission towards one or moredefined transmit sectors. Any of the user device(s) 120 (e.g., userdevices 124, 126, 128), and AP(s) 102 may be configured to perform anygiven directional reception from one or more defined receive sectors.

MIMO beamforming in a wireless network may be accomplished using RFbeamforming and/or digital beamforming. In some embodiments, inperforming a given MIMO transmission, user devices 120 and/or AP(s) 102may be configured to use all or a subset of its one or morecommunications antennas to perform MIMO beamforming.

Any of the user devices 120 (e.g., user devices 124, 126, 128), andAP(s) 102 may include any suitable radio and/or transceiver fortransmitting and/or receiving radio frequency (RF) signals in thebandwidth and/or channels corresponding to the communications protocolsutilized by any of the user device(s) 120 and AP(s) 102 to communicatewith each other. The radio components may include hardware and/orsoftware to modulate and/or demodulate communications signals accordingto pre-established transmission protocols. The radio components mayfurther have hardware and/or software instructions to communicate viaone or more Wi-Fi and/or Wi-Fi direct protocols, as standardized by theInstitute of Electrical and Electronics Engineers (IEEE) 802.11standards. In certain example embodiments, the radio component, incooperation with the communications antennas, may be configured tocommunicate via 2.4 GHz channels (e.g. 802.11b, 802.11g, 802.11n,802.11ax), 5 GHz channels (e.g. 802.11n, 802.11ac, 802.11ax), or 60 GHZchannels (e.g. 802.11ad, 802.11ay, 802.11az). 800 MHz channels (e.g.802.11ah). The communications antennas may operate at 28 GHz and 40 GHz.It should be understood that this list of communication channels inaccordance with certain 802.11 standards is only a partial list and thatother 802.11 standards may be used (e.g., Next Generation Wi-Fi, orother standards). In some embodiments, non-Wi-Fi protocols may be usedfor communications between devices, such as Bluetooth, dedicatedshort-range communication (DSRC), Ultra-High Frequency (UHF) (e.g. IEEE802.11af, IEEE 802.22), white band frequency (e.g., white spaces), orother packetized radio communications. The radio component may includeany known receiver and baseband suitable for communicating via thecommunications protocols. The radio component may further include a lownoise amplifier (LNA), additional signal amplifiers, ananalog-to-digital (A/D) converter, one or more buffers, and digitalbaseband.

In one embodiment, and with reference to FIG. 1, the AP 102 and/or theuser devices 120 may exchange sounding frames 142 (e.g., NDPs, NDPAs,trigger frames, etc.) and measurement reports 144 (e.g., LMRs) as shownin FIGS. 2A and 2B. The sounding frames 142 and LMRs 144 may be used inchannel sounding operations as explained further herein.

It is understood that the above descriptions are for purposes ofillustration and are not meant to be limiting.

FIG. 2A depicts a schematic diagram for a trigger-based channel soundingprocess 200, in accordance with one or more example embodiments of thepresent disclosure. In IEEE 802.11 communications, channel soundingrefers to a process that allows devices to evaluate radiofrequency (RF)channels used for wireless communications. The IEEE 802.11 technicalstandards define processes for devices to exchange packets, such asNDPs, and use the NDPs to determine channel characteristics, determinerelative device positions, and identify attempted attacks.

Referring to FIG. 2A, an AP 202 may perform trigger-based channelsounding with an STA 204 and an STA 206, in accordance with the IEEE802.11 standards. The AP 202 may send a trigger frame (TF) 208 (e.g., aframe that indicates to addressed devices are to send responses to theAP 202). In response to receiving the TF 208, the STA 204 may send anuplink (UL) NDP 210, and the STA 206 may send a UL NDP 212 as part ofthe channel sounding process (e.g., an NDP may lack a payload). Once theAP 202 has received the UL NDPs 210 and 212, the AP 202 may announcethat it also will sound the channel by sending an NDP-announcement(NDPA) 214 frame announcing that a downlink NDP 216 is to betransmitted, and then transmitting the DL NDP 216. Based on the DL NDP216, the STAs 204 and 206 both may determine CSI and other channelinformation, and may generate and send LMRs to the AP 202 (e.g., the STA204 may generate and send LMR 218, and the STA 206 may generate and sendLMR 220). For example, the LMRs 218 and 220 may include the respectiveToA of the DL NDP 216 at the STA 204 and the STA 206, along with theToDs and the PS of the UL NDP 210 and 212. The AP 202 may generate andsend LMR 222 to the STAs 204 and 206, the LMR 222 including the ToAs ofthe UL NDPs 210 and 212, and the ToD and PS of the DL NDP 216 (or apreviously sent DL NDP).

FIG. 2B depicts a schematic diagram for a non-trigger-based channelsounding process 250, in accordance with one or more example embodimentsof the present disclosure. FIG. 2B refers to a sounding process similarto that in FIG. 2A, but without requiring a trigger frame.

Referring to FIG. 2B, an AP 252 may perform trigger-based channelsounding with an STA 254 and an STA 256, in accordance with the IEEE802.11 standards. The AP 252 may send an NDPA 258 to announce thesending of a DL NDP 260, and may send the DL NDP 260. The STAs 254 and256 may receive the DL NDP 260 and respond by sending UL NDPs (e.g., theSTA 254 may send UL NDP 262, and the STA 256 may send UL NDP 264). Afterexchanging UL and DL NDPs, the AP 252 and the STAs 254 and 256 maygenerate and send respective LMRs. The STA 254 may send LMR 266, the STA256 may send LMR 268, and the AP 252 may send LMR 270. The LMRs mayinclude ToAs of frames received, ToDs of frames sent, and PS of framessent by the respective device sending the LMR.

FIG. 3A depicts an illustrative system 300 for a channel soundingprocess, in accordance with one or more example embodiments of thepresent disclosure.

Referring to FIG. 3A, the system 300 may include multiple devices (e.g.,STA 1, STA 2) performing channel sounding. For example, the STA 2 maysend a first sounding signal 302 and a second sounding signal 304 (e.g.,NDPs as shown in FIGS. 2A and 2B). The second sounding signal 304 mayreflect off of object 306 (e.g., an object or person), resulting in adifferent ToA than the ToA of the first sounding signal 302 at STA 1. Asshown in FIG. 3A, the first arrival at STA 1 may be the ToA of the firstsounding signal 302, and the second arrival at STA 1 may be the ToA ofthe second sounding signal 304. As shown, the magnitude of the firstsounding signal 302 may be greater than the magnitude of the secondsounding signal 304 (e.g., because the second sounding signal 304reflected off of the object 306, which may be further away from STA 1than is STA 2).

While not shown, the process may be bidirectional, in which case STA 1may send sounding signals to STA 2 similar to the first sounding signal302 and the second sounding signal 304, using the same paths, but in theopposite direction. The channel responses at both STAs should be thesame, allowing for the STAs to determine whether any ToA is fake andlikely generated by an attacker as shown in FIG. 3B.

FIG. 3B depicts an illustrative system 350 for a channel soundingprocess when an attacker exists, in accordance with one or more exampleembodiments of the present disclosure.

Referring to FIG. 3B, the system 350 may include multiple devices (e.g.,STA 1, STA 2) performing channel sounding. An attacker device 352 withan oscillator 354 may attempt to replicate sounding signals sent by STA2, which may have an oscillator 356. For example, the STA 2 may send afirst sounding signal 358 and a second sounding signal 360 (e.g., NDPsas shown in FIGS. 2A and 2B). The second sounding signal 360 may reflectoff of object 361 (e.g., an object or person), resulting in a differentToA than the ToA of the first sounding signal 358 at STA 1. The attackerdevice 352 may receive a third sounding signal 362 from STA 2 and mayreplicate the third sounding signal 362 by sending a fourth soundingsignal 364 and a fifth sounding signal 366, intended to arrive at STA 1before the first sounding signal 358 and the second sounding signal 360.

Still referring to FIG. 3B, the estimated channel response in theforward direction (e.g., from STA 2 to STA 1) may include a fake firstarrival (e.g., the ToA of the fourth sounding signal 364), a fake secondarrival (e.g., the ToA of the fifth sounding signal 366), a true firstarrival (e.g., the ToA of the first sounding signal 358), and a truesecond arrival (e.g., the ToA of the second sounding signal 360. Thefifth sounding signal 366 may arrive at STA 1 later than the fourthsounding signal 364 (e.g., because it may reflect off of an object 363),but before the second sounding signal 360 to perpetrate an attack.Similarly, the fourth sounding signal 364 may arrive at STA 1 before thefirst sounding signal 358 to perpetrate an attack.

It is difficult for the attacker device 352 to generate the same fakemultipaths in bidirectional soundings as the sounding signals sent bySTA 1 and STA 2 such that the phases, delays, and amplitudes relative tothe true multipaths are the same in both directions. To generate thesame fake multipaths in both directions, the attacker device 352 needsthe perfect calibration of the transmit and receive chains, the perfectsynchronization to the intended transmitter clock (e.g., via theoscillator 354), the fine resolution detection of the multipaths in thereceived signal, and the knowledge of the randomized sounding signal.Among the difficulties, the synchronization needs to occur at the phaselevel not frequency level. The fine resolution multipath detection isalso very challenging. Small multipaths need to be detected in thepresence of the interferences from the strong multipaths. Furthermore,the attacker device 352 usually needs some time to analyze the beginningpart of the received signal (e.g., the third sounding signal 362) sothat the attacker device 352 can detect which sounding signal is beingsent, and then sends the remaining part of the sounding signal with atime shift (e.g., the fourth sounding signal 364 and the fifth soundingsignal 366). Therefore, the attacker's sounding signal for generatingthe fake first arrival is usually incomplete. Provided the difficulties,there are mismatches in channel responses estimated from the twodirections as shown in FIG. 3B.

The mismatched responses (e.g., in the forward and reversed directions)in FIG. 3B may be used by the STAs to detect the attack and trigger analert. In the measure report of current 11az secure mode, only {time ofarrival (ToA), time of departure (ToD)} or {ToD, phase shift (PS)} aresent. There is no amplitude and phase information about the individualmultipaths or the overall picture of the multipaths.

FIG. 4A depicts a signal constellation 400 using phase shift keying, inaccordance with one or more example embodiments of the presentdisclosure.

Referring to FIG. 4A the constellation 400 shown is an 8PSK (phase shiftkeying) constellation in which each phase (e.g., angle) has the sameamplitude A.

FIG. 4B depicts a signal constellation 450 using quadrature amplitudemodulation, in accordance with one or more example embodiments of thepresent disclosure.

Referring to FIG. 4B the constellation 450 shown is an 64QAM (quadratureamplitude modulation) constellation in which the different phases havedifferent amplitudes (e.g., distances from the 0,0 origin of the axes).

While FIG. 4A and FIG. 4B represent different constellations, othermodulation and phase shift keying techniques may correspond to differentconstellations.

FIG. 5A depicts an example technique 500 for enhanced channel sounding,in accordance with one or more example embodiments of the presentdisclosure.

Referring to FIG. 5A, the technique 500 represents an extension of the802.11az sounding signal. In 802.11az, the symbol on each subcarrier mayhave the same magnitude (e.g., amplitude). The magnitude changes may beallowed across the subcarriers. For example, 16-, 64-, 256-, 1024-, orhigher order QAMs may be used (e.g., FIG. 4B) for modulation of thesounding signal. As a result, not only the number of phases increasesfrom the 8PSK or QPSK, but also the magnitude carries additional bits.Therefore, the entropy of the sounding signal increases. The selectionof the constellation point on each active subcarrier may be determinedby the output bits of a cypher like the current 802.11az.

In one or more embodiments, even though an attacker may only observe thebeginning part of the sounding signal, the attacker may performfrequency-domain detection by converting the time-domain signal tofrequency domain (e.g., by a windowed FFT). Because the windowed FFTintroduces inter-subcarrier interference, the attacker needs somecomputation power to detect the QAM symbols on the subcarriers. However,the inter-subcarrier interference reduces as the window size increases.The attacker may be able to detect most of the QAM symbols afterobserving 80-90% of sounding signal, for example, and may generate anattack signal in the remaining 10-20% sounding time.

A signal's peak to average power ratio (PAPR) is relevant in channelsounding. In particular, a large PAPR may not be optimal for channelsounding, as a time-domain signal peak may be clipped, resulting innoise, bit error, and interference, thereby causing a distorted channelestimation. Data packets, such as sounding NDPs, may use 64QAM, whichmay experience a high PAPR. In this manner, by using higher order QAMsto vary amplitude, the sounding signal may be more difficult for anattacker to identify and copy, but with some risk of signal peakclipping and distorted channel estimation. Current channel soundingpackets do not vary the signal amplitude with higher order QAMs in partbecause of the distortion risk.

In one or more embodiments, a long training field (LTF) of a soundingsignal (e.g., the UL NDP 210 of FIG. 2A, the UL NDP 212 of FIG. 2A, theDL NDP 216 of FIG. 2A, DL NDP 260 of FIG. 2B, the UL NDP 262 of FIG. 2B,the UL NDP 264 of FIG. 2B) may be generated to include a sequence forsecure mode communications. There may be 122 non-zero entries in the20-MHz secure 2×LTF sequence. The mapping of pseudo random octets may beto the non-zero entries of the 20-MHz secure 2×LTF sequence, and thenthe 64-QAM values for each non-zero entry of the secure LTF sequence maybe constructed. There may be up to 64¹²² secure LTF sequences availableto be selected in an NDP for 20-MHz secure 2×LTF, as there are up toeight repetitions and up to eight secure LTF sequences within arepetition. For notational convenience each entry of the LTF sequencemay be indicated with the integer k, which is an integer between zeroand sixty three. A table may provide the pseudo random octet index foreach nonzero subcarrier index in the secure LTF sequence. All entries inthe secure LTF sequence other than the non-zero entries shall be set tozero. The six least significant bits (B0,B1,B2,B3,B4,B5) of an octet,taking values from zero to sixty three, are used in the construction ofthe 64-QAM value for a 20-MHz secure sounding NPD, a 40-MHz securesounding NDP, an 80-MHz secure sounding NDP, and a 160-MHz securesounding NDP.

The current HE-LTF defined by the 802.11 standards consists of a fixedor predefined sequence of BPSK symbols across the active subcarriers,which are not random. The secure mode of 802.11az replaces the fixedBPSK symbol sequence with a random 64QAM symbol sequence. The 802.11azlong training field is referred to as HEz-LTF to be different from theconventional HE-LTF used in non-secure mode.

FIG. 5B depicts an example technique 520 for enhanced channel sounding,in accordance with one or more example embodiments of the presentdisclosure.

Referring to FIG. 5B, to address a possible attack signal, time domainpulses 522 independent in time may be used as illustrated. Because thepolarity or phase and/or magnitude of each pulse may be independent ofthe others, the attacker may not obtain any information about thecurrent part of the sounding signal by analyzing a previous part of thesounding signal.

However, there may be limited choices for the time limited pulses 522.For example, one option is the pulse being generated by setting all theactive subcarriers to be the same value (e.g., 1). The shape of thispulse may be close to a rectangle. The corresponding sounding signal(i.e., a sequence of pulses) may experience very little inter-pulseinterference in the time domain. The attacker can detect the polarity orphase or magnitude of the pulse by analyzing the beginning part of pulseand generate an attack signal attacking the remaining part. For a 20 MHzsounding signal, the rectangular pulse width is about 50 ns. Theattacker can generate a fake arrival ahead of the actual ones by 20 ns(i.e. 7 meters) if the receiver device does not have an attack detectionmechanism. For time limited pulses other than the rectangle, theattacker can use a Viterbi algorithm to detect the polarity or phase ormagnitude of the pulse by observing the beginning part of the pulse.

FIG. 5C depicts an example technique 530 for enhanced channel sounding,in accordance with one or more example embodiments of the presentdisclosure.

Referring to FIG. 5C, to address an attack on a time limited pulse,strong inter-signal interference may need to be introduced asillustrated in FIG. 5C. Instead of a time limited pulse, a referencesignal may have the duration the same as the sounding signal. Thereference signal may be generated from the QAM symbols in the frequencydomain the same way as the legacy OFDM symbol. The QAM symbols may bedetermined by the output bits of a cypher like the current 802.11az. Thesounding signal consists of the reference signal and its (cyclically)shifted copies that may have different polarities or phases or/andmagnitudes as illustrated in FIG. 5C. Namely, the time limited pulse inFIG. 5B may be replaced by the reference signal in FIG. 5C. The polarityor phase or magnitude of the shifted signals may be determined by theoutput bits of a cypher.

To make the system even more secure, instead of using shifted copies ofthe same reference signal, different reference signals may be used inFIG. 5C. Namely, the sounding signal consists of the superimposition ofdifferent reference signals. Each reference signal may be generated froma different set of QAM symbols in frequency domain. A different (cyclic)shift may be applied to each reference signal.

In general, the solution in FIG. 5C makes the sounding signal look likeGaussian signal in both time and frequency domains, which maximizes theentropy of each sample in time and frequency so that the attacker has ahard time to detect the sounding signal.

FIG. 5D depicts an example technique for enhanced channel sounding, inaccordance with one or more example embodiments of the presentdisclosure.

Referring to FIG. 5D, this option is the simplest extension of theexisting solution in 802.11az secure mode. One possibility is using afully random QPSK sequence to replace the 8PSK Golay sequence in802.11az secure mode. Since the constellation points are denser in 8PSKthan QPSK, the fully random 8PSK sequence is more secure than fullyrandom QPSK sequence. It increases the entropy of the sounding signaland thus makes the attacker harder to detect the transmitting soundingsignal. To enhance the security, 8PSK or 16PSK or higher order PSKconstellation may be used for the secure mode. The PSK constellation hasthe same magnitude that sounds each active subcarrier with the samepower. This makes the consistency check across the repeated soundingsmore stable than using a constellation with multiple magnitudes like16QAM.

There are two ways to enhance the existing 802.11az secure mode. First,fully random 8PSK or 16PSK or higher order PSK sequences may be used toreplace the existing 8PSK Golay sequences. For the fully random PSKsequence, the PSK symbols of the sequence are independently specified bythe encryption bits, which are generated by a cypher using someexchanged parameters or are received from the other ranging party.Second, instead of replacing the Golay sequence by a fully randomsequence, the Golay structure of 11az may be reused, but increase theconstellation from 8PSK to a higher order PSK (e.g., 16PSK or 32PSK).The second method maintains the Golay structure so that the peak toaverage power ratio (PAPR) of the sounding signal in time domain issmaller than those of the fully random sequences. The smaller PAPRenables a higher transmission power and a longer working range for802.11az.

FIG. 5E depicts an example technique 550 for enhanced channel sounding,in accordance with one or more example embodiments of the presentdisclosure.

Referring to FIG. 5E, the transformation from the encryption bits to thesounding signal should be unknown to the attacker so that it is hard forthe attacker to detect the encryption bits by observing part of thesounding signal. The modulation like OFDM and direct sequence spreadspectrum (DSSS), and the QAM mapping like Grey mapping, may betransformations known to the attacker. It may be beneficial to have atransformation unknown to the attacker as illustrated in FIG. 5E.

FIG. 5F depicts an example technique 560 for enhanced channel sounding,in accordance with one or more example embodiments of the presentdisclosure.

Referring to FIG. 5F, to reuse the existing components in a transceiver,it may be beneficial to add a transformation before the inverse fastFourier transform (IFFT) in FIG. 5F, which is unknown to the attacker,as illustrated in FIG. 5G.

FIG. 5G depicts an example technique 570 for enhanced channel sounding,in accordance with one or more example embodiments of the presentdisclosure.

In FIG. 5G, the transformation M is unknown to the attacker and may bechanged for each sounding or each measurement. It is desirable that eachelement of the output vector of the transformation M should bedetermined jointly by all the encryption bits at the input vector. As aresult, the attacker has to detect the encryption bits jointly insteadof a divide-and-conquer fashion. The transformation M may be linear ornon-linear. If it is non-linear, the operations of permutation andreplacement may be applied. The input of M may be of N symbols each witha small alphabet e.g. QPSK or 16QAM and the output of M may be of Lsymbols each with a large alphabet whose size is desired to be anexponential (or quadratic or cubic function of N). For simplicity, N maybe equal to L. Similarly, for simplicity, M may be linear as: x=s, (1)where s is the input symbol vector; and x is the output symbol vector.For even power distribution, M may be a unitary matrix, whose columns(or rows) are orthogonal with each other. In addition, the norms of thecolumns (or rows) of M may be the same. For example, a discrete Fouriertransform (DFT_matrix is a unitary matrix. For another example, arotation matrix is a unitary matrix. In fact, a unitary matrix can beviewed as a rotation matrix. The unitary matrix can be parametrized invarious ways such as the Givens angles in 802.11n/ac/ax and theHouseholder vectors in the 802.16e/m technical standard.

FIG. 6A depicts an example technique 600 for enhanced channel sounding,in accordance with one or more example embodiments of the presentdisclosure.

Referring to FIG. 6A, because the attacker may learn the transformationM after listening to the soundings, the transformation M needs to varywith soundings. For example, it may be beneficial to have a large set ofM matrixes such that the attacker may not know which of them is used fora specific sounding. As illustrated in FIG. 6A, the parameters of thetransformation M may be determined by some of the encryption bits. Theoutput of M are controlled by two parts, the input symbols and theparameters of M as illustrated in FIG. 6A. If the dimension of M islarge enough e.g. greater than 100 or if the set of M is large enough,the input symbols may be fixed e.g. [1, 0, . . . 0] or [1, . . . 1] i.e.carrying no information for simplicity because the parameters of Malready carry enough entropy for security protection. If a fixed inputvector [1, 0, . . . 0] is used, the output vector is essentially thefirst column of M. Namely, the other columns of M are not used for thesecurity protection. For the example of 802.11az sounding with 20 MHzbandwidth, there are 128 subcarriers. The matrix M can be 128 by 128. Itcan be parameterized by 16,256 Givens angles, whose ranges are (0,2π]and [0, π/2], respectively. Similar to the compressed feedback of802.11n/ac/ax, the encryption bits can specify the Givens angles. If ahigher security level is required, some encryption bits may be used tospecify the various input symbols for the input vector s in Equation (1)above. For example, BPSK or QPSK symbols may be specified by theencryption bits.

A simplified way to generate a large set of M matrixes is permutation.The rows and/or the columns of a specific M matrix can be permuted togenerate different M matrixes. The encryption bits specify thepermutation of the M matrix. This technique is equivalent to permutingthe elements of the input vector s before applying the transformationand then permuting the elements of the output vector x. Since theelements of the M matrix just move to other positions instead ofchanging to other values, the security protection level is not as highas the methods that change the values of the elements.

The matrix M in FIGS. 5G and 6A is of N by P, where N is the number ofsubcarriers (or active subcarriers) and P is the number of QAM symbolsto be mixed together. Note that, P is not necessarily to be equal to Nfor reducing the complexity. For large bandwidths, the size of M islarge e.g. 1024 and the matrix multiplications are of high complexities.For a low complexity, special matrixes with structures may be used asthe matrix M e.g. binary matrix, FFT (or IFFT) matrix, and Hadamardmatrix such that the complexity of the matrix multiplication is low. Forexample, the binary matrix with 1s and −1s only involve sign andaddition operations. For another example, QPSK matrix with {1, −1, j, −j} or {±1±j} also only involve sign and addition operations. For a thirdexample, the complexity of the FFT (or IFFT) matrix multiplication isO(N log N), which is lower than O(N²). In addition, the existinghardward for FFT (or IFFT) can be reused. Since the special matrix maybe known to the attacker, some operations unknown to the attacker mayneed to be added after the matrix multiplication for further protectingthe security. Two options are listed next.

FIG. 6B depicts an example technique 620 for enhanced channel sounding,in accordance with one or more example embodiments of the presentdisclosure.

Referring to FIG. 6B, the technique 620 is a special case for thetechnique 600 of FIG. 6A. After the matrix multiplication with M, theelements in the output vector x in Equation (1) above are permuted. Forlow complexity, the permutation may be constant and thus may be known tothe attacker. For high security, the permutation varies so that it isunknown to the attacker. The total number of permutation combinations isN!, where N is the number of subcarriers (or active subcarriers). Thecomplexity is prohibitive for the attacker to search for the permutationbeing used in a sending signal. For a simple implementation of thepermutation, block interleavers may be used. A block interleaver mayread in data symbols sequentially and fill out the rows of theinterleaver row by row. When the data is read out, the data are read outcolumn by column such that the symbol order is different from the onewhen the symbols are read in. The rows or columns do not need to befully filled.

In the existing 802.11 system, interleavers are widely used. A parsermay be added before the interleavers. The parser distributes input bitsto different interleavers and then each interleaver permutes the bitsdistributed to the interleaver. The interleaved bits at the output ofthe interleavers are finally concatenated as the interleaved bits of theoverall interleaving process. This idea can be reused here.

In FIG. 6B, some examples of interleaver are illustrated. In the topportion FIG. 6B, two block interleavers are used. The number of blockinterleavers is limited when a single block interleaver is used for thewhole permutation. For example, for N=128, there are only less than 128block interleavers such that the attacker may be able to use brute forcesearch to find the interleaver being used. To increase the number ofpermutations, multiple block interleavers may be used. In the topportion FIG. 6B, two interleavers are serially concatenated. The totalnumber of permutations is then multiplied e.g. close to N×N. For highsecurity, more than two block interleavers can be used. In the bottomportion FIG. 6B, an example using a parser and interleavers isillustrated. The elements of input vector x are first interleaved andparsed. The parsed elements are distributed to multiple interleavers,respectively. The elements distributed to each interleaver areinterleaved and the interleaved elements from the interleavers areconcatenated for the next step. For simplicity, the first interleaverwith parameters (L1, K1) may be not used, i.e. no interleaving beforeparsing, where L1 and K1 are the numbers for rows and columns of theblock interleaver, respectively. The number of permutations ismultiplied by choosing different block interleaver parameters i.e.L_(i)s and K_(i)s.

The permutation operation can be included in the matrix multiplicationof Equation (1) above by permuting the rows of M.

FIG. 6C depicts an example technique 630 for enhanced channel sounding,in accordance with one or more example embodiments of the presentdisclosure.

Referring to FIG. 6C, instead of permutation, masking can be used toprotect the security. It may be desired to prevent the attacker fromseeing the individual encryption symbols in both time and frequencydomains. For example, 802.15.4z UWB ranging sends individual time domainpulses sequentially, where the pulses are not interfered with eachother. The attacker can predict the ending part of the pulse bydetecting the beginning parting of the pulse without the interferencefrom the other pulses. For another example, OFDM modulation sendsindividual frequency domain QAM symbols, where the QAM symbols do notinterfere with each other. The individual signals in the two exampleshave low entropies such that the attacker can detect them reliably. Itmay be desirable that the attacker always observes mixed signals withhigh entropies in both the time and frequency domain.

In FIG. 6C, encryption bits generate two sets of the symbols. One is theQAM symbols to be mixed by the matrix M. The other is the sequence ofmasking symbols, which are multiplied with the mixed symbols in vector xof (1), respectively. For simplicity, the masking symbols may be of BPSKor QPSK e.g. {+1, −1} or {1, −1, j, −j}, or {1+j, 1−j, −1+j, −1−j} suchthat the masking operation only involves sign (and addition) operation.The encryption bits in FIG. 6C can be generated by a cypher like in the802.11az standard. In one embodiment, the M matrix is the FFT matrix.

The options aforementioned can be jointly used together. For the ease ofimplementation, the number of the rows of matrix M may be a power of 2(e.g., 128 and 1024). Some subcarriers may be reserved for DC, edges,and/or pilots. Therefore, if the number of the permuted or maskedsymbols (e.g., 128) is greater than that of the subcarriers availablefor carrying the secure sounding signal (e.g., 118), some permuted ormasked symbols may not be used (i.e., not mapped to the subcarriers).

FIG. 6D depicts an example transformation matrix 640 for enhancedchannel sounding, in accordance with one or more example embodiments ofthe present disclosure.

The mixing of the encryption bits or symbols in FIGS. 5G and 6Apreferably may be unknown to the attacker. In FIGS. 6B and 6C,permutation and scrambling are used such that the transformation M inFIG. 5G is unknown to the attacker and the transformation M remains arotation matrix i.e. a unitary matrix. For the ease of implementation,the encryption symbols may be mixed by a filter. The filter can belinear or nonlinear. For linear filters, finite impulse response (FIR)or infinite impulse response (IIR) can be used. Although the linearfilters can be implemented in the form of the transformation matrix M asillustrated in FIG. 6D, the conventional delay taps are of a lowcomplexity. Namely, the encryption symbols carrying the encryption bitsare passed through a linear filter with registers to get mixed signalsat the output of the filter. For FIR filters, the larger the number oftaps the securer of the system. For IIR filters, the number of taps maynot need to be large, but the precision requirement may need to be high.Otherwise, the cumulative errors at the end of the output can be large.Both linear filters may need initialization and termination. Theregisters may be initialized by all zeros. Or, the input symbols to thefilters may be treated in a circular or wrap around fashion. Forexample, the beginning and the end of the input symbols are connectedwith each other such that the input symbols form a loop. The symbols atthe end can be used for the initialization of the beginning ones. Forsimplicity, the filter taps may be chosen from a finite (or structured)alphabet for a low complexity. For example, the alphabet may be {+1,−1}or {1+j, −1+j, 1−j, −1−j}, which may not incur real multiplications inthe filter operation.

In one or more embodiments, the transformation matrix 640 (M) for linearfilters may have a Toeplitz structure.

When the attacker observes the beginning portion of the sounding signaland converted the observed signal into frequency domain. The windowedFFT introduces inter-carrier interferences. It is similar to applying aFIR filter, which is the spectrum of the windowing function, to signalson each subcarrier. If the window size is a quarter of the soundingsignal, the number of significant taps of the FIR filter is about 11,which is not a large number for the attacker to break the system.Additional filter taps may be introduced, which expands the taps due tothe windowing, by the sounding transmitter. This makes it difficult forthe attacker to break the system.

FIG. 6E depicts an example technique 650 for enhanced channel sounding,in accordance with one or more example embodiments of the presentdisclosure.

The encryption bits or symbol mixing in FIGS. 5G, 6A, 6C, and 6D maycause unequal sounding powers across frequency as illustrated in FIG.6E. For a specific sounding, some subcarriers may not have enoughsounding signal power. This may reduce the accuracy of channelestimation or time of arrival (ToA) estimation. In addition, differentsoundings for the same channels may have different sounding powerprofiles across frequency. This may affect the consistency check used byattack detection.

To mitigate the problem, the magnitude range of the sounding signal onthe subcarriers may be limited. For example, a minimum limit can be set.If the sounding signal on a subcarrier is below the limit, the signal isboosted to the minimum limit. Similarly, a maximum limit can be set. Ifthe sounding signal on a subcarrier is above the limit, the signal iscaped to the maximum limit. Since the limits may be known to theattacker, it is desirable that the magnitude outside the range limits ismapped to a value inside the range limits not always at the limits. Forexample, mod operation may be used as Equation (2):

a _(out) =a _(MIN)+mod(a _(in) −a _(MIN) , a _(MAX) −a _(MIN)),  (2)

where a_(in) and a_(out) are input and output magnitudes, respectively;a_(MAX) and a_(MIN) are the upper and lower limits of the magnitudes,respectively.

In another mitigation option, the encryption bits or symbols mixing inFIGS. 5G, 6A, 6C, and 6D may cause unequal sounding powers acrossfrequency as illustrated in FIG. 6E. For a specific sounding, somesubcarriers may not have enough sounding signal power. This may reducethe accuracy of channel estimation or time of arrival (ToA) estimation.In addition, different soundings for the same channels may havedifferent sounding power profiles across frequency. This may affect theconsistency check used by attack detection.

For constant sounding power across frequency, high order PSK signal(e.g. 16PSK and higher PSK) may be used. For low order PSK signals (e.g.8PSK), the attacker may observe the beginning part (e.g. ¼ of thesounding signal) and use Viterbi equalizer in the frequency domain todetect the transmitting signals on each subcarrier so that the attackercan regenerate the sounding signal with a time shift. For security,randomized phase rotations may be applied to the PSK symbols on thesubcarriers, respectively. The randomized phase rotation is unknown tothe attacker but known to the intended receiver. The rotated phases maybe determined part of the encryption bits.

To further increase the sounding signal entropy, the phase of eachsubcarrier may be jointly determined by all or a large portion of theencryption bits. For example, the ideas in the previous options can bereused. The symbol vector in Equation (1) and the QAM symbols in FIGS.5G-6C can be replaced by angle vector or angles. The angles aredetermined by the encryption bits. For example, the two encryption bitsselects one angle out of {0 degree, 90 degrees, 180 degrees, 270degree}. The angles picked from a finite alphabet are then transformedby mixing and/or scrambling. For the ease of implementation, Hadamardmatrix, FFT matrix, IFFT matrix, or linear filters may be used for themixing. After the transformation, some output angles may be removed foraccommodating the DC and edge subcarriers and the remaining are used asthe phases for the active subcarriers in the sounding.

As compared with the other options whose signal magnitude can varyacross subcarriers, the security level of this option is reduced due tothe entropy reduction in magnitude.

FIG. 6F depicts an example technique 660 for enhanced channel sounding,in accordance with one or more example embodiments of the presentdisclosure.

In one mitigation option, high order QAM is used for the ease ofimplementation. However, since the attacker knows the constellation, theattacker can observe the beginning part of the sounding signal anddetect the QAM symbols e.g. using Viterbi equalizer and sphere decoderin frequency domain. To make the detection difficult for the attacker,the constellation of each subcarrier can be changed. For example, it canbe rotated by an angle, which may be unknown to the attacker. An exampleis shown in FIG. 6F. Since the original QAM constellation is symmetricabout real axis, imaginary axis, and the origin, the rotation angles canbe chosen from (0 degree, 90 degrees] or [0 degree, 90 degrees). Forexample, {0, π/4}, {0, π/8, π/4, 3π/8}, or nπ/N for n =0, 1, . . . ,┌N/2┐−1. For each active subcarrier, some of the encryption bits selectthe constellation point from the constellation and some encryption bitsselect the rotation. Since the attacker only know the constellation butdoesn't know the rotation angle, the attacker has to search theconstellations for all the angles. For the example in FIG. 6F, the eightconstellation points from the two constellations are the increasedsearch space. This increases the search space and reduces the successrate of the attack.

FIG. 6G depicts an example technique 670 for enhanced channel sounding,in accordance with one or more example embodiments of the presentdisclosure.

Referring to FIG. 6G, it is desirable that the previous portion of asounding signal does not provide information about the remaining portionof the sounding signal so that the attacker cannot learn from theprevious portion to predict the remaining portion. From thisperspective, time domain pulses with a limited pulse duration are anoption. However, if the pulse duration is long and the pulse shape isknown to the attacker, the attacker can send the ending portion of thepulse with a time advancement by detecting the beginning of the pulse.Therefore, it may be beneficial to either to reduce the pulse durationor to make the pulse shape unknown to the attacker. Increasing thesounding signal bandwidth can reduce the pulse duration. However, for agiven 20 MHz bandwidth whose pulse duration is longer than 50 ns, thepulse shape may need to be unknown to the attacker.

For generating different pulses unknown to the attacker, a deltafunction or reference pulse is passed through a filter as illustrated inFIG. 6G. In FIG. 6G, the reference pulse on the top portion may be adelta function or a Nyquist pulse or a time domain signal whose spectrumis a constant across the active subcarriers. A shaping filter isillustrated in the middle portion of FIG. 6G. The shaping filter is forchanging the shape and the effective width of the reference pulse. A newpulse is generated by filtering the reference pulse using the shapingfilter. The new pulse is illustrated in the bottom portion of FIG. 6G.

Still referring to FIG. 6G, the effective width of the shaped pulse maybe wider than the reference pulse's width. The wider width is desirablefor generating inter-symbol interference among the shaped pulses sentsequentially. Namely, the wider width causes overlaps among the soundingpulse sequence such that the attacker cannot detect the polarity orphase or amplitude of the overlapped pulses easily. In another word, thesecurity of the sounding signal is protected by the inter-pulseinterference. From another viewpoint, the shaping filter introducesartificial multipaths at the sounding transmitter, which are unknown tothe attacker. For high level of security, more than ten taps may bedesired. Furthermore, the effective width of shaped pulse is desired tocause inter-pulse interference among more than ten shaped pulses suchthat the complexity for undoing the inter-pulse interference isprohibitive for the attacker, who may not know the shaping filter taps.The taps of the shaping filter may be determined by encryption bits. Inaddition, the taps may be chosen from QAM constellation e.g. 16-, 64-,and 256-QAM for the ease of implementation.

FIG. 6H depicts an example technique 680 for enhanced channel sounding,in accordance with one or more example embodiments of the presentdisclosure.

An example of generating the sounding signal is illustrated in FIG. 6H.From the left to the right, part of the encryption bits determine a setof QAM symbols e.g. QPSK or 16QAM or 64QAM symbols, which may bemultiplied with the reference pulses, respectively. After FFT or DFT,some part of the output signals may be punctured or removed to make roomfor DC and edge subcarriers. After the puncturing, the remaining signalsare loaded onto the active subcarriers in frequency domain before goinginto time domain. The IFFT or IDFT converts the loaded signals to timedomain. If there is no puncturing for the DC and edge subcarriers, thetime domain signals may consist of Nyquist pulses e.g. sinc pulses,where the reference pulse is a Nyquist pulse. The puncturing introducessome inter-pulse interference such that the reference pulse is not atrue Nyquist pulse. Before transmission, the reference pulses are shapedfor adding strong inter-pulse interferences and getting a pulse shapeunknown to the attacker. The pulse shaping can be implemented as an FIRfilter. In addition, circular convolution may be used in the pulseshaping. For example, for 20 MHz sounding, there are 128 QAM symbolsbefore FFT, 122 active subcarriers before IFFT, 128 samples for thereference pulses before pulse shaping, and still 128 time samples afterthe pulse shaping with circular convolution.

FIG. 6I depicts an example technique 690 for enhanced channel sounding,in accordance with one or more example embodiments of the presentdisclosure.

The idea of introducing multipaths in FIG. 6H may be applied to anysounding signal (e.g. the 8PSK-Golay in the 802.11az technical standard)and the other options in the disclosure. For example, the soundingtransmitter may first generate the sounding signal using OFDM and QAMmodulations and then pass the sounding signal to a multipath filter toadd inter-symbol interference as illustrated in FIG. 6I. The multipathfilter may be the same the shaping filter as in FIG. 6H. The multipathfilter may be an FIR filter and the filtering operation may be circularconvolution. Since the attacker may not know the filter taps of themultipath filter, the detection complexity of the QAM symbol isincreased exponentially with the number of taps in the multipath filter.The multipath taps are determined by part of the encryption bits and theencryption bits are known to the intended receiver. The intendedreceiver can undo the effect of introduced multipaths and estimate thetime of arrival of the sounded channel.

The example in FIG. 6I adds inter-symbol interference in the timedomain.

FIG. 6J depicts an example technique 695 for enhanced channel sounding,in accordance with one or more example embodiments of the presentdisclosure.

The interference introduced by the sounding transmitter can be added infrequency domain as illustrated in FIG. 6J, which is a special case ofthe schemes in FIGS. 5G, 6A, 6C, and 6D. The inter-carrier interference(ICI) filter can be an FIR filter, whose filter taps may be unknown tothe attacker. Circular convolution may be used by the ICI filter.

It is understood that the above descriptions are for purposes ofillustration and are not meant to be limiting.

FIG. 7 illustrates a flow diagram of illustrative process 700 forenhanced channel sounding, in accordance with one or more exampleembodiments of the present disclosure.

At block 702, a device (e.g., the user device(s) 120 and/or the AP 102of FIG. 1, the AP 202 of FIG. 2A, the STA 204 or 206 of FIG. 2A, the AP252 of FIG. 2B, the STA 254 or 256 of FIG. 2B) may generate one or moresymbols for channel sounding (e.g., channel sounding symbols). Thechannel sounding symbols may be included in one or more HEz-LTF fieldsof a sounding frame (e.g., the NPDs of FIGS. 2A and 2B), for which thenumber of symbols may depend on the number of space-time streams used intransmission and/or based on a number of users associated with thetransmission. The symbols may be generated using any of the enhancedtechniques shown in FIGS. 5A-6J. For example, any symbol may includemultiple frequency subcarriers, and the amplitude of the subcarriers ofa symbol may vary (e.g., as shown in FIG. 5A). In this manner, thenumber of constellation points of the symbols may be greater than thenumber of constellation points used in some existing channel soundingsymbols (e.g., those generated using 8PSK or other techniques where theamplitude of the subcarriers remains the same across all subcarriers ofa HE-LTF sounding symbol). The subcarrier values of the sounding symbolsmay be random values (e.g., using 64QAM).

At block 704, the device may generate an 802.11az secure mode soundingsignal (e.g., sounding/ranging NDP) that includes the one or moresounding symbols. The sounding signal may be trigger-based (e.g., inresponse to a received trigger frame as shown in FIG. 2A) ornon-trigger-based (e.g., as shown in FIG. 2B). The sounding symbols maybe proceeded in the sounding signal by other fields, such as an HE-SIG-Afield and an HE-STF field.

At block 706, the device may send the 802.11az secure mode soundingsignal. The 802.11az secure mode sounding signal may be sent as part ofa channel sounding process according to FIG. 2A or FIG. 2B, for example.

It is understood that the above descriptions are for purposes ofillustration and are not meant to be limiting.

FIG. 8 shows a functional diagram of an exemplary communication station800, in accordance with one or more example embodiments of the presentdisclosure. In one embodiment, FIG. 8 illustrates a functional blockdiagram of a communication station that may be suitable for use as an AP102 (FIG. 1) or a user device 120 (FIG. 1) in accordance with someembodiments. The communication station 800 may also be suitable for useas a handheld device, a mobile device, a cellular telephone, asmartphone, a tablet, a netbook, a wireless terminal, a laptop computer,a wearable computer device, a femtocell, a high data rate (HDR)subscriber station, an access point, an access terminal, or otherpersonal communication system (PCS) device.

The communication station 800 may include communications circuitry 802and a transceiver 810 for transmitting and receiving signals to and fromother communication stations using one or more antennas 801. Thecommunications circuitry 802 may include circuitry that can operate thephysical layer (PHY) communications and/or medium access control (MAC)communications for controlling access to the wireless medium, and/or anyother communications layers for transmitting and receiving signals. Thecommunication station 800 may also include processing circuitry 806 andmemory 808 arranged to perform the operations described herein. In someembodiments, the communications circuitry 802 and the processingcircuitry 806 may be configured to perform operations detailed in theabove figures, diagrams, and flows.

In accordance with some embodiments, the communications circuitry 802may be arranged to contend for a wireless medium and configure frames orpackets for communicating over the wireless medium. The communicationscircuitry 802 may be arranged to transmit and receive signals. Thecommunications circuitry 802 may also include circuitry formodulation/demodulation, upconversion/downconversion, filtering,amplification, etc. In some embodiments, the processing circuitry 806 ofthe communication station 800 may include one or more processors. Inother embodiments, two or more antennas 801 may be coupled to thecommunications circuitry 802 arranged for sending and receiving signals.The memory 808 may store information for configuring the processingcircuitry 806 to perform operations for configuring and transmittingmessage frames and performing the various operations described herein.The memory 808 may include any type of memory, including non-transitorymemory, for storing information in a form readable by a machine (e.g., acomputer). For example, the memory 808 may include a computer-readablestorage device, read-only memory (ROM), random-access memory (RAM),magnetic disk storage media, optical storage media, flash-memory devicesand other storage devices and media.

In some embodiments, the communication station 800 may be part of aportable wireless communication device, such as a personal digitalassistant (PDA), a laptop or portable computer with wirelesscommunication capability, a web tablet, a wireless telephone, asmartphone, a wireless headset, a pager, an instant messaging device, adigital camera, an access point, a television, a medical device (e.g., aheart rate monitor, a blood pressure monitor, etc.), a wearable computerdevice, or another device that may receive and/or transmit informationwirelessly.

In some embodiments, the communication station 800 may include one ormore antennas 801. The antennas 801 may include one or more directionalor omnidirectional antennas, including, for example, dipole antennas,monopole antennas, patch antennas, loop antennas, microstrip antennas,or other types of antennas suitable for transmission of RF signals. Insome embodiments, instead of two or more antennas, a single antenna withmultiple apertures may be used. In these embodiments, each aperture maybe considered a separate antenna. In some multiple-input multiple-output(MIMO) embodiments, the antennas may be effectively separated forspatial diversity and the different channel characteristics that mayresult between each of the antennas and the antennas of a transmittingstation.

In some embodiments, the communication station 800 may include one ormore of a keyboard, a display, a non-volatile memory port, multipleantennas, a graphics processor, an application processor, speakers, andother mobile device elements. The display may be an LCD screen includinga touch screen.

Although the communication station 800 is illustrated as having severalseparate functional elements, two or more of the functional elements maybe combined and may be implemented by combinations ofsoftware-configured elements, such as processing elements includingdigital signal processors (DSPs), and/or other hardware elements. Forexample, some elements may include one or more microprocessors, DSPs,field-programmable gate arrays (FPGAs), application specific integratedcircuits (ASICs), radio-frequency integrated circuits (RFICs) andcombinations of various hardware and logic circuitry for performing atleast the functions described herein. In some embodiments, thefunctional elements of the communication station 800 may refer to one ormore processes operating on one or more processing elements.

Certain embodiments may be implemented in one or a combination ofhardware, firmware, and software. Other embodiments may also beimplemented as instructions stored on a computer-readable storagedevice, which may be read and executed by at least one processor toperform the operations described herein. A computer-readable storagedevice may include any non-transitory memory mechanism for storinginformation in a form readable by a machine (e.g., a computer). Forexample, a computer-readable storage device may include read-only memory(ROM), random-access memory (RAM), magnetic disk storage media, opticalstorage media, flash-memory devices, and other storage devices andmedia. In some embodiments, the communication station 800 may includeone or more processors and may be configured with instructions stored ona computer-readable storage device.

FIG. 9 illustrates a block diagram of an example of a machine 900 orsystem upon which any one or more of the techniques (e.g.,methodologies) discussed herein may be performed. In other embodiments,the machine 900 may operate as a standalone device or may be connected(e.g., networked) to other machines. In a networked deployment, themachine 900 may operate in the capacity of a server machine, a clientmachine, or both in server-client network environments. In an example,the machine 900 may act as a peer machine in peer-to-peer (P2P) (orother distributed) network environments. The machine 900 may be apersonal computer (PC), a tablet PC, a set-top box (STB), a personaldigital assistant (PDA), a mobile telephone, a wearable computer device,a web appliance, a network router, a switch or bridge, or any machinecapable of executing instructions (sequential or otherwise) that specifyactions to be taken by that machine, such as a base station. Further,while only a single machine is illustrated, the term “machine” shallalso be taken to include any collection of machines that individually orjointly execute a set (or multiple sets) of instructions to perform anyone or more of the methodologies discussed herein, such as cloudcomputing, software as a service (SaaS), or other computer clusterconfigurations.

Examples, as described herein, may include or may operate on logic or anumber of components, modules, or mechanisms. Modules are tangibleentities (e.g., hardware) capable of performing specified operationswhen operating. A module includes hardware. In an example, the hardwaremay be specifically configured to carry out a specific operation (e.g.,hardwired). In another example, the hardware may include configurableexecution units (e.g., transistors, circuits, etc.) and a computerreadable medium containing instructions where the instructions configurethe execution units to carry out a specific operation when in operation.The configuring may occur under the direction of the executions units ora loading mechanism. Accordingly, the execution units arecommunicatively coupled to the computer-readable medium when the deviceis operating. In this example, the execution units may be a member ofmore than one module. For example, under operation, the execution unitsmay be configured by a first set of instructions to implement a firstmodule at one point in time and reconfigured by a second set ofinstructions to implement a second module at a second point in time.

The machine (e.g., computer system) 900 may include a hardware processor902 (e.g., a central processing unit (CPU), a graphics processing unit(GPU), a hardware processor core, or any combination thereof), a mainmemory 904 and a static memory 906, some or all of which may communicatewith each other via an interlink (e.g., bus) 908. The machine 900 mayfurther include a power management device 932, a graphics display device910, an alphanumeric input device 912 (e.g., a keyboard), and a userinterface (UI) navigation device 914 (e.g., a mouse). In an example, thegraphics display device 910, alphanumeric input device 912, and UInavigation device 914 may be a touch screen display. The machine 900 mayadditionally include a storage device (i.e., drive unit) 916, a signalgeneration device 918 (e.g., a speaker), an enhanced sounding for securemode device 919, a network interface device/transceiver 920 coupled toantenna(s) 930, and one or more sensors 928, such as a globalpositioning system (GPS) sensor, a compass, an accelerometer, or othersensor. The machine 900 may include an output controller 934, such as aserial (e.g., universal serial bus (USB), parallel, or other wired orwireless (e.g., infrared (IR), near field communication (NFC), etc.)connection to communicate with or control one or more peripheral devices(e.g., a printer, a card reader, etc.)). The operations in accordancewith one or more example embodiments of the present disclosure may becarried out by a baseband processor. The baseband processor may beconfigured to generate corresponding baseband signals. The basebandprocessor may further include physical layer (PHY) and medium accesscontrol layer (MAC) circuitry, and may further interface with thehardware processor 902 for generation and processing of the basebandsignals and for controlling operations of the main memory 904, thestorage device 916, and/or the enhanced sounding for secure mode device919. The baseband processor may be provided on a single radio card, asingle chip, or an integrated circuit (IC).

The storage device 916 may include a machine readable medium 922 onwhich is stored one or more sets of data structures or instructions 924(e.g., software) embodying or utilized by any one or more of thetechniques or functions described herein. The instructions 924 may alsoreside, completely or at least partially, within the main memory 904,within the static memory 906, or within the hardware processor 902during execution thereof by the machine 900. In an example, one or anycombination of the hardware processor 902, the main memory 904, thestatic memory 906, or the storage device 916 may constitutemachine-readable media.

The enhanced sounding for secure mode device 919 may carry out orperform any of the operations and processes (e.g., process 700)described and shown above.

It is understood that the above are only a subset of what the enhancedsounding for secure mode device 919 may be configured to perform andthat other functions included throughout this disclosure may also beperformed by the enhanced sounding for secure mode device 919.

While the machine-readable medium 922 is illustrated as a single medium,the term “machine-readable medium” may include a single medium ormultiple media (e.g., a centralized or distributed database, and/orassociated caches and servers) configured to store the one or moreinstructions 924.

Various embodiments may be implemented fully or partially in softwareand/or firmware. This software and/or firmware may take the form ofinstructions contained in or on a non-transitory computer-readablestorage medium. Those instructions may then be read and executed by oneor more processors to enable performance of the operations describedherein. The instructions may be in any suitable form, such as but notlimited to source code, compiled code, interpreted code, executablecode, static code, dynamic code, and the like. Such a computer-readablemedium may include any tangible non-transitory medium for storinginformation in a form readable by one or more computers, such as but notlimited to read only memory (ROM); random access memory (RAM); magneticdisk storage media; optical storage media; a flash memory, etc.

The term “machine-readable medium” may include any medium that iscapable of storing, encoding, or carrying instructions for execution bythe machine 900 and that cause the machine 900 to perform any one ormore of the techniques of the present disclosure, or that is capable ofstoring, encoding, or carrying data structures used by or associatedwith such instructions. Non-limiting machine-readable medium examplesmay include solid-state memories and optical and magnetic media. In anexample, a massed machine-readable medium includes a machine-readablemedium with a plurality of particles having resting mass. Specificexamples of massed machine-readable media may include non-volatilememory, such as semiconductor memory devices (e.g., electricallyprogrammable read-only memory (EPROM), or electrically erasableprogrammable read-only memory (EEPROM)) and flash memory devices;magnetic disks, such as internal hard disks and removable disks;magneto-optical disks; and CD-ROM and DVD-ROM disks.

The instructions 924 may further be transmitted or received over acommunications network 926 using a transmission medium via the networkinterface device/transceiver 920 utilizing any one of a number oftransfer protocols (e.g., frame relay, internet protocol (IP),transmission control protocol (TCP), user datagram protocol (UDP),hypertext transfer protocol (HTTP), etc.). Example communicationsnetworks may include a local area network (LAN), a wide area network(WAN), a packet data network (e.g., the Internet), mobile telephonenetworks (e.g., cellular networks), plain old telephone (POTS) networks,wireless data networks (e.g., Institute of Electrical and ElectronicsEngineers (IEEE) 802.11 family of standards known as Wi-Fi®, IEEE 802.16family of standards known as WiMax®), IEEE 802.15.4 family of standards,and peer-to-peer (P2P) networks, among others. In an example, thenetwork interface device/transceiver 920 may include one or morephysical jacks (e.g., Ethernet, coaxial, or phone jacks) or one or moreantennas to connect to the communications network 926. In an example,the network interface device/transceiver 920 may include a plurality ofantennas to wirelessly communicate using at least one of single-inputmultiple-output (SIMO), multiple-input multiple-output (MIMO), ormultiple-input single-output (MISO) techniques. The term “transmissionmedium” shall be taken to include any intangible medium that is capableof storing, encoding, or carrying instructions for execution by themachine 900 and includes digital or analog communications signals orother intangible media to facilitate communication of such software.

The operations and processes described and shown above may be carriedout or performed in any suitable order as desired in variousimplementations. Additionally, in certain implementations, at least aportion of the operations may be carried out in parallel. Furthermore,in certain implementations, less than or more than the operationsdescribed may be performed.

FIG. 10 is a block diagram of a radio architecture 105A, 105B inaccordance with some embodiments that may be implemented in any one ofthe example AP 102 and/or the example STA 120 of FIG. 1. Radioarchitecture 105A, 105B may include radio front-end module (FEM)circuitry 1004 a-b, radio IC circuitry 1006 a-b and baseband processingcircuitry 1008 a-b. Radio architecture 105A, 105B as shown includes bothWireless Local Area Network (WLAN) functionality and Bluetooth (BT)functionality although embodiments are not so limited. In thisdisclosure, “WLAN” and “Wi-Fi” are used interchangeably.

FEM circuitry 1004 a-b may include a WLAN or Wi-Fi FEM circuitry 1004 aand a Bluetooth (BT) FEM circuitry 1004 b. The WLAN FEM circuitry 1004 amay include a receive signal path comprising circuitry configured tooperate on WLAN RF signals received from one or more antennas 1001, toamplify the received signals and to provide the amplified versions ofthe received signals to the WLAN radio IC circuitry 1006 a for furtherprocessing. The BT FEM circuitry 1004 b may include a receive signalpath which may include circuitry configured to operate on BT RF signalsreceived from one or more antennas 1001, to amplify the received signalsand to provide the amplified versions of the received signals to the BTradio IC circuitry 1006 b for further processing. FEM circuitry 1004 amay also include a transmit signal path which may include circuitryconfigured to amplify WLAN signals provided by the radio IC circuitry1006 a for wireless transmission by one or more of the antennas 1001. Inaddition, FEM circuitry 1004 b may also include a transmit signal pathwhich may include circuitry configured to amplify BT signals provided bythe radio IC circuitry 1006 b for wireless transmission by the one ormore antennas. In the embodiment of FIG. 10, although FEM 1004 a and FEM1004 b are shown as being distinct from one another, embodiments are notso limited, and include within their scope the use of an FEM (not shown)that includes a transmit path and/or a receive path for both WLAN and BTsignals, or the use of one or more FEM circuitries where at least someof the FEM circuitries share transmit and/or receive signal paths forboth WLAN and BT signals.

Radio IC circuitry 1006 a-b as shown may include WLAN radio IC circuitry1006 a and BT radio IC circuitry 1006 b. The WLAN radio IC circuitry1006 a may include a receive signal path which may include circuitry todown-convert WLAN RF signals received from the FEM circuitry 1004 a andprovide baseband signals to WLAN baseband processing circuitry 1008 a.BT radio IC circuitry 1006 b may in turn include a receive signal pathwhich may include circuitry to down-convert BT RF signals received fromthe FEM circuitry 1004 b and provide baseband signals to BT basebandprocessing circuitry 1008 b. WLAN radio IC circuitry 1006 a may alsoinclude a transmit signal path which may include circuitry to up-convertWLAN baseband signals provided by the WLAN baseband processing circuitry1008 a and provide WLAN RF output signals to the FEM circuitry 1004 afor subsequent wireless transmission by the one or more antennas 1001.BT radio IC circuitry 1006 b may also include a transmit signal pathwhich may include circuitry to up-convert BT baseband signals providedby the BT baseband processing circuitry 1008 b and provide BT RF outputsignals to the FEM circuitry 1004 b for subsequent wireless transmissionby the one or more antennas 1001. In the embodiment of FIG. 10, althoughradio IC circuitries 1006 a and 1006 b are shown as being distinct fromone another, embodiments are not so limited, and include within theirscope the use of a radio IC circuitry (not shown) that includes atransmit signal path and/or a receive signal path for both WLAN and BTsignals, or the use of one or more radio IC circuitries where at leastsome of the radio IC circuitries share transmit and/or receive signalpaths for both WLAN and BT signals.

Baseband processing circuity 1008 a-b may include a WLAN basebandprocessing circuitry 1008 a and a BT baseband processing circuitry 1008b. The WLAN baseband processing circuitry 1008 a may include a memory,such as, for example, a set of RAM arrays in a Fast Fourier Transform orInverse Fast Fourier Transform block (not shown) of the WLAN basebandprocessing circuitry 1008 a. Each of the WLAN baseband circuitry 1008 aand the BT baseband circuitry 1008 b may further include one or moreprocessors and control logic to process the signals received from thecorresponding WLAN or BT receive signal path of the radio IC circuitry1006 a-b, and to also generate corresponding WLAN or BT baseband signalsfor the transmit signal path of the radio IC circuitry 1006 a-b. Each ofthe baseband processing circuitries 1008 a and 1008 b may furtherinclude physical layer (PHY) and medium access control layer (MAC)circuitry, and may further interface with a device for generation andprocessing of the baseband signals and for controlling operations of theradio IC circuitry 1006 a-b.

Referring still to FIG. 10, according to the shown embodiment, WLAN-BTcoexistence circuitry 1013 may include logic providing an interfacebetween the WLAN baseband circuitry 1008 a and the BT baseband circuitry1008 b to enable use cases requiring WLAN and BT coexistence. Inaddition, a switch 1003 may be provided between the WLAN FEM circuitry1004 a and the BT FEM circuitry 1004 b to allow switching between theWLAN and BT radios according to application needs. In addition, althoughthe antennas 1001 are depicted as being respectively connected to theWLAN FEM circuitry 1004 a and the BT FEM circuitry 1004 b, embodimentsinclude within their scope the sharing of one or more antennas asbetween the WLAN and BT FEMs, or the provision of more than one antennaconnected to each of FEM 1004 a or 1004 b.

In some embodiments, the front-end module circuitry 1004 a-b, the radioIC circuitry 1006 a-b, and baseband processing circuitry 1008 a-b may beprovided on a single radio card, such as wireless radio card 1002. Insome other embodiments, the one or more antennas 1001, the FEM circuitry1004 a-b and the radio IC circuitry 1006 a-b may be provided on a singleradio card. In some other embodiments, the radio IC circuitry 1006 a-band the baseband processing circuitry 1008 a-b may be provided on asingle chip or integrated circuit (IC), such as IC 1012.

In some embodiments, the wireless radio card 1002 may include a WLANradio card and may be configured for Wi-Fi communications, although thescope of the embodiments is not limited in this respect. In some ofthese embodiments, the radio architecture 105A, 105B may be configuredto receive and transmit orthogonal frequency division multiplexed (OFDM)or orthogonal frequency division multiple access (OFDMA) communicationsignals over a multicarrier communication channel. The OFDM or OFDMAsignals may comprise a plurality of orthogonal subcarriers.

In some of these multicarrier embodiments, radio architecture 105A, 105Bmay be part of a Wi-Fi communication station (STA) such as a wirelessaccess point (AP), a base station or a mobile device including a Wi-Fidevice. In some of these embodiments, radio architecture 105A, 105B maybe configured to transmit and receive signals in accordance withspecific communication standards and/or protocols, such as any of theInstitute of Electrical and Electronics Engineers (IEEE) standardsincluding, 802.11n-2009, IEEE 802.11-2012, IEEE 802.11-2016,802.11n-2009, 802.11ac, 802.11ah, 802.11ad, 802.11 ay and/or 802.11axstandards and/or proposed specifications for WLANs, although the scopeof embodiments is not limited in this respect. Radio architecture 105A,105B may also be suitable to transmit and/or receive communications inaccordance with other techniques and standards.

In some embodiments, the radio architecture 105A, 105B may be configuredfor high-efficiency Wi-Fi (HEW) communications in accordance with theIEEE 802.11ax standard. In these embodiments, the radio architecture105A, 105B may be configured to communicate in accordance with an OFDMAtechnique, although the scope of the embodiments is not limited in thisrespect.

In some other embodiments, the radio architecture 105A, 105B may beconfigured to transmit and receive signals transmitted using one or moreother modulation techniques such as spread spectrum modulation (e.g.,direct sequence code division multiple access (DS-CDMA) and/or frequencyhopping code division multiple access (FH-CDMA)), time-divisionmultiplexing (TDM) modulation, and/or frequency-division multiplexing(FDM) modulation, although the scope of the embodiments is not limitedin this respect.

In some embodiments, as further shown in FIG. 10, the BT basebandcircuitry 1008 b may be compliant with a Bluetooth (BT) connectivitystandard such as Bluetooth, Bluetooth 8.0 or Bluetooth 6.0, or any otheriteration of the Bluetooth Standard.

In some embodiments, the radio architecture 105A, 105B may include otherradio cards, such as a cellular radio card configured for cellular(e.g., 5GPP such as LTE, LTE-Advanced or 7G communications).

In some IEEE 802.11 embodiments, the radio architecture 105A, 105B maybe configured for communication over various channel bandwidthsincluding bandwidths having center frequencies of about 900 MHz, 2.4GHz, 5 GHz, and bandwidths of about 2 MHz, 4 MHz, 5 MHz, 5.5 MHz, 6 MHz,8 MHz, 10 MHz, 20 MHz, 40 MHz, 80 MHz (with contiguous bandwidths) or80+80 MHz (160 MHz) (with non-contiguous bandwidths). In someembodiments, a 920 MHz channel bandwidth may be used. The scope of theembodiments is not limited with respect to the above center frequencieshowever.

FIG. 11 illustrates WLAN FEM circuitry 1004 a in accordance with someembodiments. Although the example of FIG. 11 is described in conjunctionwith the WLAN FEM circuitry 1004 a, the example of FIG. 11 may bedescribed in conjunction with the example BT FEM circuitry 1004 b (FIG.10), although other circuitry configurations may also be suitable.

In some embodiments, the FEM circuitry 1004 a may include a TX/RX switch1102 to switch between transmit mode and receive mode operation. The FEMcircuitry 1004 a may include a receive signal path and a transmit signalpath. The receive signal path of the FEM circuitry 1004 a may include alow-noise amplifier (LNA) 1106 to amplify received RF signals 1103 andprovide the amplified received RF signals 1107 as an output (e.g., tothe radio IC circuitry 1006 a-b (FIG. 10)). The transmit signal path ofthe circuitry 1004 a may include a power amplifier (PA) to amplify inputRF signals 1109 (e.g., provided by the radio IC circuitry 1006 a-b), andone or more filters 1112, such as band-pass filters (BPFs), low-passfilters (LPFs) or other types of filters, to generate RF signals 1115for subsequent transmission (e.g., by one or more of the antennas 1001(FIG. 10)) via an example duplexer 1114.

In some dual-mode embodiments for Wi-Fi communication, the FEM circuitry1004 a may be configured to operate in either the 2.4 GHz frequencyspectrum or the 5 GHz frequency spectrum. In these embodiments, thereceive signal path of the FEM circuitry 1004 a may include a receivesignal path duplexer 1104 to separate the signals from each spectrum aswell as provide a separate LNA 1106 for each spectrum as shown. In theseembodiments, the transmit signal path of the FEM circuitry 1004 a mayalso include a power amplifier 1110 and a filter 1112, such as a BPF, anLPF or another type of filter for each frequency spectrum and a transmitsignal path duplexer 1104 to provide the signals of one of the differentspectrums onto a single transmit path for subsequent transmission by theone or more of the antennas 1001 (FIG. 10). In some embodiments, BTcommunications may utilize the 2.4 GHz signal paths and may utilize thesame FEM circuitry 1004 a as the one used for WLAN communications.

FIG. 12 illustrates radio IC circuitry 1006 a in accordance with someembodiments. The radio IC circuitry 1006 a is one example of circuitrythat may be suitable for use as the WLAN or BT radio IC circuitry 1006a/1006 b (FIG. 10), although other circuitry configurations may also besuitable. Alternatively, the example of FIG. 12 may be described inconjunction with the example BT radio IC circuitry 1006 b.

In some embodiments, the radio IC circuitry 1006 a may include a receivesignal path and a transmit signal path. The receive signal path of theradio IC circuitry 1006 a may include at least mixer circuitry 1202,such as, for example, down-conversion mixer circuitry, amplifiercircuitry 1206 and filter circuitry 1208. The transmit signal path ofthe radio IC circuitry 1006 a may include at least filter circuitry 1212and mixer circuitry 1214, such as, for example, up-conversion mixercircuitry. Radio IC circuitry 1006 a may also include synthesizercircuitry 1204 for synthesizing a frequency 1205 for use by the mixercircuitry 1202 and the mixer circuitry 1214. The mixer circuitry 1202and/or 1214 may each, according to some embodiments, be configured toprovide direct conversion functionality. The latter type of circuitrypresents a much simpler architecture as compared with standardsuper-heterodyne mixer circuitries, and any flicker noise brought aboutby the same may be alleviated for example through the use of OFDMmodulation. FIG. 12 illustrates only a simplified version of a radio ICcircuitry, and may include, although not shown, embodiments where eachof the depicted circuitries may include more than one component. Forinstance, mixer circuitry 1214 may each include one or more mixers, andfilter circuitries 1208 and/or 1212 may each include one or morefilters, such as one or more BPFs and/or LPFs according to applicationneeds. For example, when mixer circuitries are of the direct-conversiontype, they may each include two or more mixers.

In some embodiments, mixer circuitry 1202 may be configured todown-convert RF signals 1107 received from the FEM circuitry 1004 a-b(FIG. 10) based on the synthesized frequency 1205 provided bysynthesizer circuitry 1204. The amplifier circuitry 1206 may beconfigured to amplify the down-converted signals and the filtercircuitry 1208 may include an LPF configured to remove unwanted signalsfrom the down-converted signals to generate output baseband signals1207. Output baseband signals 1207 may be provided to the basebandprocessing circuitry 1008 a-b (FIG. 10) for further processing. In someembodiments, the output baseband signals 1207 may be zero-frequencybaseband signals, although this is not a requirement. In someembodiments, mixer circuitry 1202 may comprise passive mixers, althoughthe scope of the embodiments is not limited in this respect.

In some embodiments, the mixer circuitry 1214 may be configured toup-convert input baseband signals 1211 based on the synthesizedfrequency 1205 provided by the synthesizer circuitry 1204 to generate RFoutput signals 1109 for the FEM circuitry 1004 a-b. The baseband signals1211 may be provided by the baseband processing circuitry 1008 a-b andmay be filtered by filter circuitry 1212. The filter circuitry 1212 mayinclude an LPF or a BPF, although the scope of the embodiments is notlimited in this respect.

In some embodiments, the mixer circuitry 1202 and the mixer circuitry1214 may each include two or more mixers and may be arranged forquadrature down-conversion and/or up-conversion respectively with thehelp of synthesizer 1204. In some embodiments, the mixer circuitry 1202and the mixer circuitry 1214 may each include two or more mixers eachconfigured for image rejection (e.g., Hartley image rejection). In someembodiments, the mixer circuitry 1202 and the mixer circuitry 1214 maybe arranged for direct down-conversion and/or direct up-conversion,respectively. In some embodiments, the mixer circuitry 1202 and themixer circuitry 1214 may be configured for super-heterodyne operation,although this is not a requirement.

Mixer circuitry 1202 may comprise, according to one embodiment:quadrature passive mixers (e.g., for the in-phase (I) and quadraturephase (Q) paths). In such an embodiment, RF input signal 1107 from FIG.12 may be down-converted to provide I and Q baseband output signals tobe sent to the baseband processor.

Quadrature passive mixers may be driven by zero and ninety-degreetime-varying LO switching signals provided by a quadrature circuitrywhich may be configured to receive a LO frequency (fLO) from a localoscillator or a synthesizer, such as LO frequency 1205 of synthesizer1204 (FIG. 12). In some embodiments, the LO frequency may be the carrierfrequency, while in other embodiments, the LO frequency may be afraction of the carrier frequency (e.g., one-half the carrier frequency,one-third the carrier frequency). In some embodiments, the zero andninety-degree time-varying switching signals may be generated by thesynthesizer, although the scope of the embodiments is not limited inthis respect.

In some embodiments, the LO signals may differ in duty cycle (thepercentage of one period in which the LO signal is high) and/or offset(the difference between start points of the period). In someembodiments, the LO signals may have an 85% duty cycle and an 80%offset. In some embodiments, each branch of the mixer circuitry (e.g.,the in-phase (I) and quadrature phase (Q) path) may operate at an 80%duty cycle, which may result in a significant reduction is powerconsumption.

The RF input signal 1107 (FIG. 11) may comprise a balanced signal,although the scope of the embodiments is not limited in this respect.The I and Q baseband output signals may be provided to low-noiseamplifier, such as amplifier circuitry 1206 (FIG. 12) or to filtercircuitry 1208 (FIG. 12).

In some embodiments, the output baseband signals 1207 and the inputbaseband signals 1211 may be analog baseband signals, although the scopeof the embodiments is not limited in this respect. In some alternateembodiments, the output baseband signals 1207 and the input basebandsignals 1211 may be digital baseband signals. In these alternateembodiments, the radio IC circuitry may include analog-to-digitalconverter (ADC) and digital-to-analog converter (DAC) circuitry.

In some dual-mode embodiments, a separate radio IC circuitry may beprovided for processing signals for each spectrum, or for otherspectrums not mentioned here, although the scope of the embodiments isnot limited in this respect.

In some embodiments, the synthesizer circuitry 1204 may be afractional-N synthesizer or a fractional N/N+1 synthesizer, although thescope of the embodiments is not limited in this respect as other typesof frequency synthesizers may be suitable. For example, synthesizercircuitry 1204 may be a delta-sigma synthesizer, a frequency multiplier,or a synthesizer comprising a phase-locked loop with a frequencydivider. According to some embodiments, the synthesizer circuitry 1204may include digital synthesizer circuitry. An advantage of using adigital synthesizer circuitry is that, although it may still includesome analog components, its footprint may be scaled down much more thanthe footprint of an analog synthesizer circuitry. In some embodiments,frequency input into synthesizer circuity 1204 may be provided by avoltage controlled oscillator (VCO), although that is not a requirement.A divider control input may further be provided by either the basebandprocessing circuitry 1008 a-b (FIG. 10) depending on the desired outputfrequency 1205. In some embodiments, a divider control input (e.g., N)may be determined from a look-up table (e.g., within a Wi-Fi card) basedon a channel number and a channel center frequency as determined orindicated by the example application processor 1010. The applicationprocessor 1010 may include, or otherwise be connected to, one of theexample secure signal converter 101 or the example received signalconverter 103 (e.g., depending on which device the example radioarchitecture is implemented in).

In some embodiments, synthesizer circuitry 1204 may be configured togenerate a carrier frequency as the output frequency 1205, while inother embodiments, the output frequency 1205 may be a fraction of thecarrier frequency (e.g., one-half the carrier frequency, one-third thecarrier frequency). In some embodiments, the output frequency 1205 maybe a LO frequency (fLO).

FIG. 13 illustrates a functional block diagram of baseband processingcircuitry 1008 a in accordance with some embodiments. The basebandprocessing circuitry 1008 a is one example of circuitry that may besuitable for use as the baseband processing circuitry 1008 a (FIG. 10),although other circuitry configurations may also be suitable.Alternatively, the example of FIG. 12 may be used to implement theexample BT baseband processing circuitry 1008 b of FIG. 10.

The baseband processing circuitry 1008 a may include a receive basebandprocessor (RX BBP) 1302 for processing receive baseband signals 1209provided by the radio IC circuitry 1006 a-b (FIG. 10) and a transmitbaseband processor (TX BBP) 1304 for generating transmit basebandsignals 1211 for the radio IC circuitry 1006 a-b. The basebandprocessing circuitry 1008 a may also include control logic 1306 forcoordinating the operations of the baseband processing circuitry 1008 a.

In some embodiments (e.g., when analog baseband signals are exchangedbetween the baseband processing circuitry 1008 a-b and the radio ICcircuitry 1006 a-b), the baseband processing circuitry 1008 a mayinclude ADC 1310 to convert analog baseband signals 1309 received fromthe radio IC circuitry 1006 a-b to digital baseband signals forprocessing by the RX BBP 1302. In these embodiments, the basebandprocessing circuitry 1008 a may also include DAC 1312 to convert digitalbaseband signals from the TX BBP 1304 to analog baseband signals 1311.

In some embodiments that communicate OFDM signals or OFDMA signals, suchas through baseband processor 1008 a, the transmit baseband processor1304 may be configured to generate OFDM or OFDMA signals as appropriatefor transmission by performing an inverse fast Fourier transform (IFFT).The receive baseband processor 1302 may be configured to processreceived OFDM signals or OFDMA signals by performing an FFT. In someembodiments, the receive baseband processor 1302 may be configured todetect the presence of an OFDM signal or OFDMA signal by performing anautocorrelation, to detect a preamble, such as a short preamble, and byperforming a cross-correlation, to detect a long preamble. The preamblesmay be part of a predetermined frame structure for Wi-Fi communication.

Referring back to FIG. 10, in some embodiments, the antennas 1001 (FIG.10) may each comprise one or more directional or omnidirectionalantennas, including, for example, dipole antennas, monopole antennas,patch antennas, loop antennas, microstrip antennas or other types ofantennas suitable for transmission of RF signals. In some multiple-inputmultiple-output (MIMO) embodiments, the antennas may be effectivelyseparated to take advantage of spatial diversity and the differentchannel characteristics that may result. Antennas 1001 may each includea set of phased-array antennas, although embodiments are not so limited.

Although the radio architecture 105A, 105B is illustrated as havingseveral separate functional elements, one or more of the functionalelements may be combined and may be implemented by combinations ofsoftware-configured elements, such as processing elements includingdigital signal processors (DSPs), and/or other hardware elements. Forexample, some elements may comprise one or more microprocessors, DSPs,field-programmable gate arrays (FPGAs), application specific integratedcircuits (ASICs), radio-frequency integrated circuits (RFICs) andcombinations of various hardware and logic circuitry for performing atleast the functions described herein. In some embodiments, thefunctional elements may refer to one or more processes operating on oneor more processing elements.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments. The terms “computing device,” “userdevice,” “communication station,” “station,” “handheld device,” “mobiledevice,” “wireless device” and “user equipment” (UE) as used hereinrefers to a wireless communication device such as a cellular telephone,a smartphone, a tablet, a netbook, a wireless terminal, a laptopcomputer, a femtocell, a high data rate (HDR) subscriber station, anaccess point, a printer, a point of sale device, an access terminal, orother personal communication system (PCS) device. The device may beeither mobile or stationary.

As used within this document, the term “communicate” is intended toinclude transmitting, or receiving, or both transmitting and receiving.This may be particularly useful in claims when describing theorganization of data that is being transmitted by one device andreceived by another, but only the functionality of one of those devicesis required to infringe the claim. Similarly, the bidirectional exchangeof data between two devices (both devices transmit and receive duringthe exchange) may be described as “communicating,” when only thefunctionality of one of those devices is being claimed. The term“communicating” as used herein with respect to a wireless communicationsignal includes transmitting the wireless communication signal and/orreceiving the wireless communication signal. For example, a wirelesscommunication unit, which is capable of communicating a wirelesscommunication signal, may include a wireless transmitter to transmit thewireless communication signal to at least one other wirelesscommunication unit, and/or a wireless communication receiver to receivethe wireless communication signal from at least one other wirelesscommunication unit.

As used herein, unless otherwise specified, the use of the ordinaladjectives “first,” “second,” “third,” etc., to describe a commonobject, merely indicates that different instances of like objects arebeing referred to and are not intended to imply that the objects sodescribed must be in a given sequence, either temporally, spatially, inranking, or in any other manner.

The term “access point” (AP) as used herein may be a fixed station. Anaccess point may also be referred to as an access node, a base station,an evolved node B (eNodeB), or some other similar terminology known inthe art. An access terminal may also be called a mobile station, userequipment (UE), a wireless communication device, or some other similarterminology known in the art. Embodiments disclosed herein generallypertain to wireless networks. Some embodiments may relate to wirelessnetworks that operate in accordance with one of the IEEE 802.11standards.

Some embodiments may be used in conjunction with various devices andsystems, for example, a personal computer (PC), a desktop computer, amobile computer, a laptop computer, a notebook computer, a tabletcomputer, a server computer, a handheld computer, a handheld device, apersonal digital assistant (PDA) device, a handheld PDA device, anon-board device, an off-board device, a hybrid device, a vehiculardevice, a non-vehicular device, a mobile or portable device, a consumerdevice, a non-mobile or non-portable device, a wireless communicationstation, a wireless communication device, a wireless access point (AP),a wired or wireless router, a wired or wireless modem, a video device,an audio device, an audio-video (A/V) device, a wired or wirelessnetwork, a wireless area network, a wireless video area network (WVAN),a local area network (LAN), a wireless LAN (WLAN), a personal areanetwork (PAN), a wireless PAN (WPAN), and the like.

Some embodiments may be used in conjunction with one way and/or two-wayradio communication systems, cellular radio-telephone communicationsystems, a mobile phone, a cellular telephone, a wireless telephone, apersonal communication system (PCS) device, a PDA device whichincorporates a wireless communication device, a mobile or portableglobal positioning system (GPS) device, a device which incorporates aGPS receiver or transceiver or chip, a device which incorporates an RFIDelement or chip, a multiple input multiple output (MIMO) transceiver ordevice, a single input multiple output (SIMO) transceiver or device, amultiple input single output (MIS 0) transceiver or device, a devicehaving one or more internal antennas and/or external antennas, digitalvideo broadcast (DVB) devices or systems, multi-standard radio devicesor systems, a wired or wireless handheld device, e.g., a smartphone, awireless application protocol (WAP) device, or the like.

Some embodiments may be used in conjunction with one or more types ofwireless communication signals and/or systems following one or morewireless communication protocols, for example, radio frequency (RF),infrared (IR), frequency-division multiplexing (FDM), orthogonal FDM(OFDM), time-division multiplexing (TDM), time-division multiple access(TDMA), extended TDMA (E-TDMA), general packet radio service (GPRS),extended GPRS, code-division multiple access (CDMA), wideband CDMA(WCDMA), CDMA 2000, single-carrier CDMA, multi-carrier CDMA,multi-carrier modulation (MDM), discrete multi-tone (DMT), Bluetooth®,global positioning system (GPS), Wi-Fi, Wi-Max, ZigBee, ultra-wideband(UWB), global system for mobile communications (GSM), 2G, 2.5G, 3G,3.5G, 4G, fifth generation (5G) mobile networks, 3GPP, long termevolution (LTE), LTE advanced, enhanced data rates for GSM Evolution(EDGE), or the like. Other embodiments may be used in various otherdevices, systems, and/or networks.

The following examples pertain to further embodiments.

Example 1 may include a device comprising processing circuitry coupledto storage, the processing circuitry configured to: generate a channelsounding symbol comprising a first subcarrier and a second subcarrier,wherein a first amplitude of the first subcarrier is different than asecond amplitude of the second subcarrier; generate a channel soundingsignal comprising the channel sounding symbol; and send the channelsounding signal to a second device.

Example 2 may include the device of example 1 and/or some other exampleherein, wherein the channel sounding signal is a null data packet (NDP).

Example 3 may include the device of example 1 and/or some other exampleherein, wherein to generate the channel sounding symbol comprises togenerate the channel sounding symbol using a 16 quadrature amplitudemodulation (QAM) constellation.

Example 4 may include the device of example 1 and/or some other exampleherein, wherein to generate the channel sounding symbol comprises togenerate the channel sounding symbol using a 64 QAM constellation.

Example 5 may include the device of example 1 and/or some other exampleherein, wherein to generate the channel sounding symbol comprises togenerate the channel sounding symbol using a 256 QAM constellation.

Example 6 may include the device of example 1 and/or some other exampleherein, wherein to generate the channel sounding symbol comprises togenerate the channel sounding symbol using a 1024 QAM constellation.

Example 7 may include the device of example 1 and/or some other exampleherein, wherein to generate the channel sounding symbol comprises togenerate the channel sounding symbol using a phase-shift keying (PSK)modulation.

Example 8 may include the device of example 1 and/or some other exampleherein, wherein to generate the channel sounding symbol comprises togenerate the channel sounding symbol using quadrature phase-shift keying(QPSK) modulation.

Example 9 may include the device of example 1 and/or some other exampleherein, wherein the processing circuitry is further configured to:generate a second channel sounding symbol comprising a third subcarrierand a fourth subcarrier, wherein a third amplitude of the thirdsubcarrier is different than a fourth amplitude of the fourthsubcarrier, wherein the channel sounding symbol further comprises thesecond channel sounding symbol.

Example 10 may include the device of example 1 and/or some other exampleherein, wherein the processing circuitry is further configured to:generate a secure high efficiency long training field (HEz-LTF)comprising the channel sounding symbol, wherein the channel soundingsymbol further comprises the HEz-LTF.

Example 11 may include the device of example 1 and/or some other exampleherein, further comprising a transceiver configured to transmit andreceive wireless signals.

Example 12 may include the device of example 1 and/or some other exampleherein, further comprising an antenna coupled to the transceiver tocause to send the channel sounding signal.

Example 13 may include a non-transitory computer-readable medium storingcomputer-executable instructions which when executed by one or moreprocessors result in performing operations comprising: generating, by afirst device, a channel sounding symbol comprising a first subcarrierand a second subcarrier, wherein a first amplitude of the firstsubcarrier is different than a second amplitude of the secondsubcarrier; generating, by the first device, a channel sounding signalcomprising the channel sounding symbol; sending, by the first device,the channel sounding signal to a second device.

Example 14 may include the non-transitory computer-readable medium ofexample 13 and/or some other example herein, wherein the channelsounding signal is a null data packet (NDP).

Example 15 may include the non-transitory computer-readable medium ofexample 13 and/or some other example herein, wherein generating thechannel sounding symbol comprises generating the channel sounding symbolusing a 16 quadrature amplitude modulation (QAM) constellation.

Example 16 may include the non-transitory computer-readable medium ofexample 13 and/or some other example herein, wherein generating thechannel sounding symbol comprises generating the channel sounding symbolusing a 64 QAM or greater constellation.

Example 17 may include the non-transitory computer-readable medium ofexample 13 and/or some other example herein, wherein generating thechannel sounding symbol comprises generating the channel sounding symbolusing phase-shift keying (PSK) modulation.

Example 18 may include the non-transitory computer-readable medium ofexample 13 and/or some other example herein, wherein generating thechannel sounding symbol comprises generating the channel sounding symbolusing quadrature phase-shift keying (QPSK) modulation.

Example 19 may include a method comprising: generating, by processingcircuitry of a first device, a channel sounding symbol comprising afirst subcarrier and a second subcarrier, wherein a first amplitude ofthe first subcarrier is different than a second amplitude of the secondsubcarrier; generating, by the processing circuitry, a channel soundingsignal comprising the channel sounding symbol; sending, by theprocessing circuitry, the channel sounding signal to a second device.

Example 20 may include the method of example 19 and/or some otherexample herein, wherein generating the channel sounding symbol comprisesgenerating the channel sounding symbol using a 64 QAM or greaterconstellation.

Example 21 may include one or more non-transitory computer-readablemedia comprising instructions to cause an electronic device, uponexecution of the instructions by one or more processors of theelectronic device, to perform one or more elements of a method describedin or related to any of examples 1-20, or any other method or processdescribed herein.

Example 22 may include an apparatus comprising logic, modules, and/orcircuitry to perform one or more elements of a method described in orrelated to any of examples 1-20, or any other method or processdescribed herein.

Example 23 may include a method, technique, or process as described inor related to any of examples 1-20, or portions or parts thereof.

Example 24 may include an apparatus comprising: one or more processorsand one or more computer readable media comprising instructions that,when executed by the one or more processors, cause the one or moreprocessors to perform the method, techniques, or process as described inor related to any of examples 1-20, or portions thereof.

Example 25 may include a method of communicating in a wireless networkas shown and described herein.

Example 26 may include a system for providing wireless communication asshown and described herein.

Example 27 may include a device for providing wireless communication asshown and described herein.

Embodiments according to the disclosure are in particular disclosed inthe attached claims directed to a method, a storage medium, a device anda computer program product, wherein any feature mentioned in one claimcategory, e.g., method, can be claimed in another claim category, e.g.,system, as well. The dependencies or references back in the attachedclaims are chosen for formal reasons only. However, any subject matterresulting from a deliberate reference back to any previous claims (inparticular multiple dependencies) can be claimed as well, so that anycombination of claims and the features thereof are disclosed and can beclaimed regardless of the dependencies chosen in the attached claims.The subject-matter which can be claimed comprises not only thecombinations of features as set out in the attached claims but also anyother combination of features in the claims, wherein each featurementioned in the claims can be combined with any other feature orcombination of other features in the claims. Furthermore, any of theembodiments and features described or depicted herein can be claimed ina separate claim and/or in any combination with any embodiment orfeature described or depicted herein or with any of the features of theattached claims.

The foregoing description of one or more implementations providesillustration and description, but is not intended to be exhaustive or tolimit the scope of embodiments to the precise form disclosed.Modifications and variations are possible in light of the aboveteachings or may be acquired from practice of various embodiments.

Certain aspects of the disclosure are described above with reference toblock and flow diagrams of systems, methods, apparatuses, and/orcomputer program products according to various implementations. It willbe understood that one or more blocks of the block diagrams and flowdiagrams, and combinations of blocks in the block diagrams and the flowdiagrams, respectively, may be implemented by computer-executableprogram instructions. Likewise, some blocks of the block diagrams andflow diagrams may not necessarily need to be performed in the orderpresented, or may not necessarily need to be performed at all, accordingto some implementations.

These computer-executable program instructions may be loaded onto aspecial-purpose computer or other particular machine, a processor, orother programmable data processing apparatus to produce a particularmachine, such that the instructions that execute on the computer,processor, or other programmable data processing apparatus create meansfor implementing one or more functions specified in the flow diagramblock or blocks. These computer program instructions may also be storedin a computer-readable storage media or memory that may direct acomputer or other programmable data processing apparatus to function ina particular manner, such that the instructions stored in thecomputer-readable storage media produce an article of manufactureincluding instruction means that implement one or more functionsspecified in the flow diagram block or blocks. As an example, certainimplementations may provide for a computer program product, comprising acomputer-readable storage medium having a computer-readable program codeor program instructions implemented therein, said computer-readableprogram code adapted to be executed to implement one or more functionsspecified in the flow diagram block or blocks. The computer programinstructions may also be loaded onto a computer or other programmabledata processing apparatus to cause a series of operational elements orsteps to be performed on the computer or other programmable apparatus toproduce a computer-implemented process such that the instructions thatexecute on the computer or other programmable apparatus provide elementsor steps for implementing the functions specified in the flow diagramblock or blocks.

Accordingly, blocks of the block diagrams and flow diagrams supportcombinations of means for performing the specified functions,combinations of elements or steps for performing the specified functionsand program instruction means for performing the specified functions. Itwill also be understood that each block of the block diagrams and flowdiagrams, and combinations of blocks in the block diagrams and flowdiagrams, may be implemented by special-purpose, hardware-based computersystems that perform the specified functions, elements or steps, orcombinations of special-purpose hardware and computer instructions.

Conditional language, such as, among others, “can,” “could,” “might,” or“may,” unless specifically stated otherwise, or otherwise understoodwithin the context as used, is generally intended to convey that certainimplementations could include, while other implementations do notinclude, certain features, elements, and/or operations. Thus, suchconditional language is not generally intended to imply that features,elements, and/or operations are in any way required for one or moreimplementations or that one or more implementations necessarily includelogic for deciding, with or without user input or prompting, whetherthese features, elements, and/or operations are included or are to beperformed in any particular implementation.

Many modifications and other implementations of the disclosure set forthherein will be apparent having the benefit of the teachings presented inthe foregoing descriptions and the associated drawings. Therefore, it isto be understood that the disclosure is not to be limited to thespecific implementations disclosed and that modifications and otherimplementations are intended to be included within the scope of theappended claims. Although specific terms are employed herein, they areused in a generic and descriptive sense only and not for purposes oflimitation.

What is claimed is:
 1. A device, the device comprising processingcircuitry coupled to storage, the processing circuitry configured to:generate a channel sounding symbol comprising a first subcarrier and asecond subcarrier, wherein a first amplitude of the first subcarrier isdifferent than a second amplitude of the second subcarrier; generate achannel sounding signal comprising the channel sounding symbol; and sendthe channel sounding signal to a second device.
 2. The device of claim1, wherein the channel sounding signal is a null data packet (NDP). 3.The device of claim 1, wherein to generate the channel sounding symbolcomprises to generate the channel sounding symbol using a 16 quadratureamplitude modulation (QAM) constellation.
 4. The device of claim 1,wherein to generate the channel sounding symbol comprises to generatethe channel sounding symbol using a 64 QAM constellation.
 5. The deviceof claim 1, wherein to generate the channel sounding symbol comprises togenerate the channel sounding symbol using a 256 QAM constellation. 6.The device of claim 1, wherein to generate the channel sounding symbolcomprises to generate the channel sounding symbol using a 1024 QAMconstellation.
 7. The device of claim 1, wherein to generate the channelsounding symbol comprises to generate the channel sounding symbol usinga phase-shift keying (PSK) modulation.
 8. The device of claim 1, whereinto generate the channel sounding symbol comprises to generate thechannel sounding symbol using quadrature phase-shift keying (QPSK)modulation.
 9. The device of claim 1, wherein the processing circuitryis further configured to: generate a second channel sounding symbolcomprising a third subcarrier and a fourth subcarrier, wherein a thirdamplitude of the third subcarrier is different than a fourth amplitudeof the fourth subcarrier, wherein the channel sounding symbol furthercomprises the second channel sounding symbol.
 10. The device of claim 1,wherein the processing circuitry is further configured to: generate asecure high efficiency long training field (HEz-LTF) comprising thechannel sounding symbol, wherein the channel sounding symbol furthercomprises the HEz-LTF.
 11. The device of claim 1, further comprising atransceiver configured to transmit and receive wireless signals.
 12. Thedevice of claim 11, further comprising an antenna coupled to thetransceiver to send the channel sounding signal.
 13. A non-transitorycomputer-readable medium storing computer-executable instructions whichwhen executed by one or more processors result in performing operationscomprising: generating, by a first device, a channel sounding symbolcomprising a first subcarrier and a second subcarrier, wherein a firstamplitude of the first subcarrier is different than a second amplitudeof the second subcarrier; generating, by the first device, a channelsounding signal comprising the channel sounding symbol; and sending, bythe first device, the channel sounding signal to a second device. 14.The non-transitory computer-readable medium of claim 13, wherein thechannel sounding signal is a null data packet (NDP).
 15. Thenon-transitory computer-readable medium of claim 13, wherein generatingthe channel sounding symbol comprises generating the channel soundingsymbol using a 16 quadrature amplitude modulation (QAM) constellation.16. The non-transitory computer-readable medium of claim 13, whereingenerating the channel sounding symbol comprises generating the channelsounding symbol using a 64 QAM or greater constellation.
 17. Thenon-transitory computer-readable medium of claim 13, wherein generatingthe channel sounding symbol comprises generating the channel soundingsymbol using phase-shift keying (PSK) modulation.
 18. The non-transitorycomputer-readable medium of claim 13, wherein generating the channelsounding symbol comprises generating the channel sounding symbol usingquadrature phase-shift keying (QPSK) modulation.
 19. A methodcomprising: generating, by processing circuitry of a first device, achannel sounding symbol comprising a first subcarrier and a secondsubcarrier, wherein a first amplitude of the first subcarrier isdifferent than a second amplitude of the second subcarrier; generating,by the processing circuitry, a channel sounding signal comprising thechannel sounding symbol; and sending, by the processing circuitry, thechannel sounding signal to a second device.
 20. The method of claim 19,wherein generating the channel sounding symbol comprises generating thechannel sounding symbol using a 64 QAM or greater constellation.